WHETHER IT is a deficiency in abstract reasoning or of language skills, Miss Manners is not certain. But she does know that people who insist on taking social idiomatic expressions literally have a problem. Two problems, actually. The second one is being tiresome.

"Why did she ask me how I feel if she didn't want to hear about what I've been through?"

"I'm not going to address him as 'dear' or sign myself 'Yours truly' or 'Sincerely', when he's certainly not dear to me and I'm not truly or sincerely or any other way his."

"They told me I could stay with them any time I'm in town, and when I wrote them about next weekend, they said they already had plans and didn't offer to cancel them."

Naturally patient and tolerant, not to say saintly, with the bewildered and the uninformed, Miss Manners grows testy with people who make such arguments. She cannot believe that they honestly don't understand what a conventional phrase is. She thinks they want to strip these remarks of their nakedness. What a nasty urge that is.

However, it does occasionally happen that an expression of that sort can change its meaning somewhat, or that it could have more than one meaning, depending on how and by whom it is said. Here, therefore, is a short glossary of social idioms:

How do you do? How are you? Both of these mean Hello. The correct question, when you want to know how someone's digestion or divorce is getting along, is Tell me, how have you really been?

Call me. This can mean Don't bother me now -- let's discuss it on office time, or I would accept if you asked me out or I can't discuss this here or Don't go so fast.

I'll call you. This has opposite meanings, and you have to judge by the delivery. One is Let's start something and the other is Don't call me.

Et's have lunch. Among social acquaintances, this means If you ever have nothing to do on a day I have nothing to do, let's get together. Among business acquaintances, it means If you have something useful to say to me I'll listen.

Let's have dinner. Among social acquaintances, it means Let's advance this friendship. Among business acquaintances, it means Let's turn this into a friendship.

Please stop by sometime and see me. Said to someone who lives in the same area, it means Call me if you'd like to visit me. Genuine dropping in disappeared with the telephone, so if you want to encourage that, you have to say I'm always home in the mornings -- don't bother to call but just drop by.

Please come and stay with me. Said to someone from another area, this means I would consider extending an invitation at your convenience if it coincides with my convenience.

We must get together. Watch out here, because there are several similar expressions. This one means I like you but I'm too busy not to take on more friendship.

We really must see more of each other. One of the tricky ones, this actually meant I can't make the time to see you.

We must do this more often. Another variation -- this one is really[TEXT OMITTED FROM SOURCE] This was surprisingly enjoyable, but it's still going to happen infrequently.

Yours truly, Yours sincerely. The first is business, the second distant social. Both mean Well, I guess that's all I've got to say so I'll close now.

Is all that clear? Oh, one last thing. People who say I only say what I really mean, really mean I am about to insult you. MISS MANNERS RESPONDS

Q. I recently bought a beautiful oval dining room table. I would like to know if it would be proper to use a rectangular tablecloth on it, or if I must find an oval one. Also, my grandmother says the drop should be 6 inches, but other etiquette authorities say 12 to 18.

A. Miss Manners sides with grandmothers whenever she can, but 6 inches is not enough to cover a table decently. You don't want the flap hanging above peoples' laps. Shall we say 10 at a minimum? That way, the knees push it out of harm's way. You will never find the right tablecloths for your purposes in oval, and will break your heart over passing over ones you love because they are not oval. Rectangular ones should certainly do, but if they seem to dip too conspicuously at the corners, you could just round these parts off.

Q. Recently, a yound bride, Mary Doe, sent me a delightful note of thanks for my wedding gift to her and her husband, John Smith. I was pleasantly surprised to have my gift acknowledged quickly. But I was completely surprised to see printed at the top of the note-paper: Mr. and Mrs. John Smith-Doe. My question: Do I now introduce John as Mr. Smith-Doe? This is the first time I have met with sich a situation. I would appreciate any information you can offer concerning this custom.

A. It is one of many solutions to the problem of equal billing in marriage, none of them truly satisfactory. For example, what if the Smith-Does have a baby who marries the Jones-Roes' child; what is their child's surname? And whatever happened to Mrs. Smith-Doe's mother's original surname?

However, Miss Manners advises graciously addressing people as they wish, and the bridegroom has declared himslef Mr. Smith-Doe. The fact that the thank-you letter was prompt and delightful indicates that future issue will be well brought up, even if cumbersomely named.

Q. If a woman offers you her hand in greeting, should you grasp it, squeeze it gently, and at the same time pull her toward you and peck her on the cheek?

It would appear to me most appropriate to kiss a woman on the cheek, but if she offers you her lips instead, what should you do -- kiss her on the lips or go round to a cheek?

Once you have kissed a woman as a greeting, are you expected to continue with the practice in all future greeting situations involving that person? If you don't, is that person likely to be offended?

A. A gentleman must, in these circumstances, take what he is offered. If it is a hand, shake it. If it is a cheek, kiss it. If it is a pair of lips, kiss it. If it keeps reappearing, it must be rekissed.

Remember that we are talking about a formal, public gesture, and the fact that parts of the body and ways they are used may duplicate private expressions of emotion is irrelevent.

Just because gentlemen no longer have the exclusive right to inititate private kissing does not mean that they may now share in the ladies' privilege of initiating -- or withholding -- public kissing.

Q. My husband and I are celebrating our 50th anniversary this June. I would like my party to be a fun affair in which all can participate.

Twenty years ago, I was active at charitable functions and I pantomimed an opera record. I was considered fairly good and was asked to repeat it several times. I would like to perform at my own party, but my daughter thinks it is not proper since I am the hostess. Could you please advise me on the correct procedure since I am anxious not to spoil a beautiful party.

A. It is considered fair to warn guests when there will be performances of amateur talent at innocent-sounding social events. Miss Manners is in favor of such gatherings, and urges you to arrange a party where you and others can display their abilities. But she agrees that it is unfair to spring this on unsuspecting people when you are not only the hostess but an honoree; in other words, where you already have a double claim to center stage.