2. 外语
  3. It takes at least five to ten years ________it is possible to test this medicine on human patients.

It takes at least five to ten years ________it is possible to test this medicine on human patients.

admin2016-08-11  50
问题 It takes at least five to ten years ________it is possible to test this medicine on human patients.
选项 A、before
B、since
C、after
D、when
答案A
解析 本题考查时间状语从句。本句是before引导的时间状语从句的固定句型：it+谓语+some time+before sb．do(did)sth．，只有A项before放入句中符合。
转载请注明原文地址:https://kaotiyun.com/show/DgRO777K
0

成人本科学位英语

相关试题推荐
随机试题
最新回复(0)