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

admin2016-08-11 43

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

成人本科学位英语

相关试题推荐

随机试题

最新回复(0)