英语连词用法练习题(附详解)(2)

18. Doing your homework is a sure way to improve your test scores, and this is especially true ________ it comes to classroom tests.

A. as                       B. since                     C. when                      D. after

19. I have been keeping that photo ________ I can see it every day, as it always reminds me of my college days.

A. which                 B. where                    C. whether                  D. when

20. You may borrow this book ­­­ ________ you promise to give it back.

A. in case                B. so long as               C. as if                       D. even if

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