问题补充:
The rivers will become dirtier and dirtier we take action to protect them.
A. since
B. if
C. until
D. unless
答案:
A. since
B. if
C. until
(答案→)D. unless
解析:since由于,自从……以来;if 是否,如果; until直到;unless除非,如果不。句意:如果我们不采取措施保护他们,这些河流会越来越脏。结合语境可知选D。
时间:2019-03-24 00:16:10
The rivers will become dirtier and dirtier we take action to protect them.
A. since
B. if
C. until
D. unless
A. since
B. if
C. until
(答案→)D. unless
解析:since由于,自从……以来;if 是否,如果; until直到;unless除非,如果不。句意:如果我们不采取措施保护他们,这些河流会越来越脏。结合语境可知选D。