Training astronauts______not an easy thing.A、areB、isC、wereD、beB当分词短语作主语时,谓语动

游客2023-09-23  21

问题 Training astronauts______not an easy thing.

选项 A、are
B、is
C、were
D、be

答案 B

解析 当分词短语作主语时,谓语动词用单数,故选B。
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