you have heard the song ,you will never forget it
问题描述：
you have heard the song ,you will never forget it
( ) you have heard the song ,you will never forget itA . if B. unless C.once D.though 选哪一个,说一下理由...
答
C.once
译：一旦你听过这首歌,你将永远不会忘记.
B/D的错误应该显而易见,语意不对；
主要要甄别的是A .if.if不合适,是因为若if引导的从句表条件的话,you have heard the song 的时态不对,应该是you hear the song；否则就应该改成虚拟语气了