You better wash your hands first 这里的had可以省略?

You better wash your hands first 这里的had可以省略? You had better wash your hands at once.改祈使句 you _____ wash your hands first. But you must wash your hands first. You had detter wash your hands at once .(变成祈使句) You ( ) wash your hands () dinner You'd better wash your hands before meal.(改同义句 you had better -------TV now,Tom.Finish your homework first. (语法)Did you wash your hands well Wash your hands before you eat You mast wash your hands eating things You'd better finish your homework first.这里的'd是什么的缩写?