Happy ___ they were ,there was something missing from them .A.if _英语解答

Happy ___ they were ,there was something missing from them .A.if B.when C.since D.as
如题 ,求正解带解析-

人气：186 ℃　时间：2019-11-24 00:28:42

解答

选D,本句大意为：尽管他们很幸福,但是他们也错过一些东西.因此只有C和D字面意思符合,如果是选C的话,那么Happy一次不应置于句首,since不引导倒装句,而as可以引导.