I'msuretheletterwon'tarriveintime

发布时间：2020-07-27 04:59:38

I'm sure the letter won't arrive in time ________ it is sent by arrive in time ________ it is sent by air．A.ifB.untilC.becauseD.unless

网友回答

D解析解析：考查连词，unless引导让步状语从句
以上问题属网友观点，不代表本站立场，仅供参考！