THURSDAY: The Sand Pebbles, Gun-boat diplomacy and missionary in war-torn China in the twenties. Steve McQueen and Candice Bergan star in 1966 Robert Wise-directed adventure. Two-part showing concludes Friday. Ch. 7. 9 p.m. Color. 2 hrs.

On the Town. A catchy 1949 Gene Kelly-Frank Sinatra song and dance number. Music by Leonard Bernstein, CH. 7. 11:30 p.m. Color. 2 hrs.

FRIDAY: Twilight Zone. Agnes Moorehead is the lone and wordless star of one of the best Twilight Zone's ever. She plays an old farm woman doing lonely battle with invaders from another planet. Rod Serting script. CH. 27. 9:30 p.m. B-W. 30 min.

In Search of Ancient Astronauts, Hour-long special explores German author Erich Von Daniken's thesis that the ancient gods were visitors from outer space. CH. 4. 10 p.m. Color. 60 min.

SUNDAY: CBS News Special, An Interview with four freshman senators Huddleston (D-Ky.). Holms (R-N.C), Hathaway '(D-Me.), and Biden (D-Def.). CH. 7. Noon. Color. 90 min.

MONDAY: Jack Paar Tonite, No kidding. The mercurial late-night talk host returns to the post-prime hours, after a ten-year absence, on a one-week-a-month basis. This week's guests include actress Goldie Hawn. Once Levant's widow June, country music's Loretta Lynn, author David Halberstan '55, and candid cameraman Allen Funt. CH. 5. 11:30 p.m. Color. 90 min.

TUESDAY: America. Allstair Cooke takes his historical documentary into episode five as the pioneers cross the mountains and set out for the promised land. "Gone West" includes an exploration of the infamous deportation of the Cherokee Nation from the ancestral funds in Georgia. CH.4. 10 p.m. Color. 60 min.

WEDNESDAY: Special, Trouble Comes to Town, Small-town Southern sheriff Lloyd Bridges adopts a Northern Mack youth, the son of a Korean War buddy who saved his life, in this made-for-television movie about a town on the brink of race war. Directed by Daniel Petric ("A Raisin In the Sun"), CH. 5. 8:30 p.m. Color, 90 min.