DEAR ABBY: How many days advance notice should you give a family member before advising him that you will be coming for a visit? My nephew, "Harry," called his brother, "Milton," at 6 p.m. on a Sunday to let him know he was planning to arrive at his home the following Tuesday afternoon for a visit. (Harry rarely talks with Milton, let alone visits him.) Harry was offended when Milton didn't seem thrilled with the idea. (Milton did not say no; he said "OK.") Milton is taking care of his wife who is recovering from surgery and may have been overwhelmed at the idea of guests.

Since the world revolves around Harry, I am sure he forgot to inquire into the state of his sister-in-law's health when he called. Now Harry is refusing to visit because of what he perceived as Milton's response.

I feel it is time for this old lady to say something to this self-centered little jerk. However, before I put in my 2 cents' worth, I need to know if 36 hours is an appropriate time frame. -- CLUELESS IN CURRY VILLAGE

DEAR CLUELESS: Harry needs to polish his social graces because he, not you, is clueless. It is never appropriate to "inform" anyone that you will be coming for a visit. The polite way to do it is to ask if a visit would be convenient, so if it is NOT convenient, the potential host has an "out."

DEAR ABBY: I experienced a random act of kindness and want to share it with you.

I was driving alone from Atlanta to a small town near Greensboro, N.C. It was raining hard, and my car hydroplaned and slid off the road.

A woman returning to work after lunch saw my car, stopped, and asked me if I was OK. I assured her that I was fine, but felt a little panicky about being so far from home. She calmed me down, helped me out of my car, and invited me to sit with her in her car until help arrived.

While the police wrote up the report and the tow truck hauled my car back onto the highway, this caring lady stood next to me in the rain, keeping me dry with her umbrella. After the police were finished, she insisted that I come to her office to catch my breath and compose myself.

She telephoned some friends who worked near my final destination (which was five miles from the scene of my accident) so that I would have somewhere to go if I ran into more trouble on the road.

Then she escorted me to a nearby car repair service where a friend of hers works, and asked him to fix the minor damage to my car. He did it immediately without charging a penny –- and I was on my way within a half-hour.

Abby, I want to express the depth of my gratitude to this woman -– her name is Suzanna –- for her help and concern, and to her friend, Andrew, for fixing my car. They reminded me that good Samaritans still exist in this world. I will forever be ... GRATEFUL IN GEORGIA

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DEAR ABBY: Last March you printed a letter I wrote. In it, I told you I had expressed my desire to become the first female U.S. president, but my teacher and fellow students laughed at me.

Since writing to you, I have received a flood of support from friends, Dear Abby readers and you, yourself. But wait, there is more! I received a letter from Sen. John Kerry, and just recently, one from the White House signed by President Bush.

The fact that I received a response to my letter from that high up on the ladder of life has inspired me. I feel that I can now follow my dreams and help other young women my age to believe that they, too, can do whatever they want if they just trust themselves.

I have included a copy of what President Bush had to say, in case you want to print it, Abby. And thank you for your help. -- MARTA IN MARYLAND

DEAR MARTA: Thank you for the update, and for granting me permission to print the letter you received from President Bush. (I printed Sen. Kerry's letter last May.) That he would take time from his campaign schedule to offer you his support shows his belief in young people like yourself, who, in the years to come, will determine the future of our country. Read on:

"Dear Marta: I recently learned about your desire to be president of the United States.

"America is a great country, where people can dream big and achieve their full potential through hard work and determination. I encourage you to continue setting high goals, studying hard and helping others.

"The lessons you learn now will help you develop the character and values you need to succeed in life and become a responsible leader.

"Your idealism, hope and energy reflect the spirit of America and can help to build a better future for all our citizens.

"Mrs. Bush and I send our best wishes. May God bless you, and may God continue to bless America.

"Sincerely, George W. Bush"

DEAR ABBY: I cannot stand it when people drop in unannounced! My mother is the biggest offender. If our door isn't locked, she walks right in without knocking. My husband and I work hard all week and look forward to peace and quiet on weekends. It's disruptive when she "pops in" -- and she often stays for hours.

How can I tell her to call us before coming over? We have tried not answering the door, and even throwing on our coats like we were just leaving so she'll leave. I am so angry I can't even begin to think of a polite way to tell her to stop. -- SICK OF IT IN EAU CLAIRE, WIS.

DEAR SICK OF IT: I don't blame you for being angry, but you are placing the blame where it doesn't belong. Your mother isn't to blame for this situation -- you are.

Your mother may have no idea that you're so angry at her that you're ready to explode. Say something to her before you do. Tell your mother politely that you and your husband work hard all week and are not always prepared to entertain her on weekends. Explain that you and your husband would appreciate it if she called and arranged her visits in advance rather then dropping over. Then, if she persists, find the backbone to inform her that her visit is not convenient. Until you have the courage to act like an adult, she will continue to treat you like a child.

What teens need to know about sex, drugs, AIDS, and getting along with peers and parents is in "What Every Teen Should Know." To order, send a business-size, self-addressed envelope, plus check or money order for $5 (U.S. funds only) to: Dear Abby, Teen Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included.)

DEAR ABBY: "Mitch" and I have been best-friends-with-benefits for nine years. He has a live-in girlfriend, "Edna," and they have an 11-month-old son together. The two of them are always fighting and yelling, and I'm always the peacemaker. I helped in raising their child so often that the boy called me Mom before he said it to Edna.

Two years ago, I told Mitch I wanted to be with him -- something more than just his girl on the side. He said he already knew it, but had been waiting for me to say it. He said he felt the same way, but he wasn't ready to go from one relationship to another.

When I first told him how I felt, he told me not to wait for him. He said if I did find someone, I shouldn't hold back because of him. When I finally did meet and date someone, Mitch got into an uproar about it and said he didn't like the guy. I ended the relationship to please him.

So here I sit, committed to someone who can't do the same for me, and feeling confused and lonely. I believe I am in love with Mitch. We still have a sexual relationship. I have tried to cool things down, but when I see Mitch, I just melt. Do you think he means what he says, or is he just telling me what I want to hear for what he can get? -- MISERABLE IN CONNECTICUT

DEAR MIZ: Let's review what Mitch has been saying: He said he has known for years that you're in love with him. He also told you not to wait for him. If Mitch loved you, do you really think he'd be living with someone else and telling you to move on? I don't.

Now let's look at what Mitch has been getting: He has someone who has continued to sleep with him in spite of the fact that he lives with someone else and fathered a child with her. On top of that, you're a free baby sitter and peacemaker. Enough about what he's getting. All you're getting is heartache.

I'll give Mitch high marks for salesmanship. But you shouldn't "buy" everything he sells you.

DEAR ABBY: I am employed by a national company to tutor high school students, one-on-one. For various reasons, I suspect that one of my students -- with whom I meet every one or two weeks -- may be smoking pot.

From a professional perspective, I feel this is none of my business. From a personal perspective, and as a parent myself, I am agonizing over whether I should bring my suspicions to the attention of his parent. If I were his parent, I would certainly want to know. Then again, my suspicions could be wrong. What is the ethical thing to do? -- UNSURE IN CONCORD, CALIF.

DEAR UNSURE: Your student's welfare IS your business. It's refreshing to know that someone is debating the "ethical" thing to do these days. If media reports are accurate, they lead us to believe that ethics have gone the way of the dinosaur.

Before approaching your student's parent, talk to the boy about your concerns. His problem may be something other than pot. At least give him a chance to explain. However, if your suspicions persist, by all means tell his parent what you have told me. You'll be doing both of them a favor.

To order "How to Write Letters for All Occasions," send a business-sized, self-addressed envelope, plus check or money order for $5 (U.S. funds) to: Dear Abby -- Letter Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included in the price.)