That practically nothing happens in "Morning's at Seven," the award-winning drama at the National Theater, is true only literally.

To the characters, four elderly sisters and their immediate families, life is teeming with cosmic questions and crucial choices. Among them, they own four neighboring houses, two next door to each other forming the stage set, and two offstage within walking distance, and the possibilies these present to them for arranging their lives in different significant and adventurous ways are limitless.

Will Ida's 40-year-old son marry his fiancee of 12 years and move into the house his father is keeping empty for him, or will Cora use it to claim the first privacy of her four- decade marriage? Will Esther's husband exile her upstairs and take in his brother-in- law as a roommate? Where can Aaronetta go when she discovers that she never really had a home?

It's interesting that the audience becomes engrossed in the drama of these questions, in addition to the whimsical humor with which they are asked. Consider, in contrast, how trivial and static "Kingdoms," earlier this season, rendered the grand-scale subject of Napoleon's kidnapping the Pope.

Paul Osborn's play was written in 1939, but achieved its first success with this production, directed by Vivan Matalon, for which both got Tony Awards in 1980. The time is apparently right now for examining ordinary lives.

The actresses playing the four sisters -- two of them, Maureen O'Sullivan and Teresa Wright, gracefully extending their careers as leading ladies -- have been much acclaimed. Kate Reid and Elizabeth Wilson are also pillars of this production. But a great deal of the charm is in the very funny auxiliary characterizations -- King Donovan as a mild husband who goes into philosophical funks, in which he leans his head against a tree and ponders the road he didn't take, thus wreaking havoc on the peace; Robert Moberly, as his tightly wound son showing dangerous signs of wondering "What's it all about?"; and Charlotte Moore as his fiancee, summoning massive amounts of nervous charm and booming enthusiasm in the simple cause of getting on with the normal progress of life.

MORNING'S AT 7 -- At the National through March 14.