"The Mighty Gents," the new play at the Kennedy Center about a black Newark high school street gang 15 years later, gets A for acting, A for atomsphere and F for filosophy. (Spelling isn't counted.)

You never in your life heard so many complaints of "I'm nobody," "I'm somebody," "I'm you," " You're me," " I'm dead" and "You're dead."

The cheif symbol is a pile of yellow knitting of which the knitter says - twice - "I know what I want to do, I know what it is I have to do to get what I want, but somehow I just can't do it."

This is reference, as far as one can see from squinting at it from the orchestra, to the difficulties of knit-one, purl-two. The hero shows his compassion by asking, after she has rocked and knitted her way through the play, "Baby, how's your knitting?" At least he didn't say that life was like a dropped stitch.

The hero is the gang's war lord, whose only redeeming quality is that he likes his long-time girl friend.

He is made to look good in contrast to the alternatives, as personified by a gangster and a wino, but actually he is just less successful than the first and younger than the second.

But when you conclude that the point is that these are the only ghetto choices the gang list their relatives who made it out honorably - the sister who graduated from college "into the black bourgeois," the two dumb brothers who have their own taxi business.

This leaves the theme with nothing but the idea that it sure was fun terrorizing everyone when we were teenagers, but what are we going to do now? Fifteen years seems a long time to be asking this.

So would two hours - without intermission - if not for two extraordinary elements. First, the writing is bad only when it attempts to be deep. Richard Wesley has an excellent ear, and the unpretentious street talks is beautifully and humorously written. The major speeches may be bad, but the minor scenes are absolutely poetic.

The second powerful asset of "Mighty Gents" is its near-perfect cast. Morgan Freeman, as the wino, is spellbinding. Dorian Harewood has that shining-young-man quality of the stardom he seems to be going toward, and uses it to obscure the triviality of the hero. Starletta DuPois uses grand tragedy for the same purpose in doing the knitter. The gang, Brent Jennings, Mansoor Najee-Ullah and Richard Gant, and the father, Frank Adu, are each fresh and excellent potraits.