企源知识库

_______ come into leaf or bloom is obviously a sign of spring.
A、Trees
B、The trees
C、That trees
D、What trees
【正确答案】：C
【题目解析】：句子后面已经出现了谓语动词，由于一个句子中不能出现两个谓语动词，所以前面的___come into leaf or bloom只能做主语从句，主语从句中不缺少成份只能用that引导。