Bob promises to join in the soccer match ____he has to help his f_英语解答

Bob promises to join in the soccer match ____he has to help his father on the farm.A.if B.unless C.as D.when
为什么呢?

人气：478 ℃　时间：2019-09-05 08:59:29

解答

unless 表示除非.整句的意思是,除非Bob必须要去农场帮他父亲,他就会参加足球赛.