If you're of a certain age, you can close your eyes and hear Dinah Shore exhorting you to ''See the USA in your Chevrolet!'' and picture her putting her hand over her mouth to blow you a big, corny kiss: Mmmmmmm-wah! Shore, who died Feb. 24 at the age of 77 from cancer, was also the only serious golfer who ever dated both Burt Reynolds and Iggy Pop. A big-band singer with a hit- or-miss movie career (1943's Thank Your Lucky Stars, 1944's Up in Arms), Shore really came into her own on TV in the '50s: As the host of The Dinah Shore Chevy Show, she used her honeyed Tennessee twang to put guests at ease and to sell cars with equal, innocent sincerity. In the '70s, her daytime talk show Dinah's Place showcased her mixture of chipper politeness and a certain ribald earthiness, no easy combo to pull off when you're interviewing Joey Bishop or Hubert Humphrey. Send her memory a big mmmmm-wah!