wasn't it?

A. wondering B. wandering C. walking D. speaking

17. My friend, Tom , left New York in 1976 and _______ since then.

A. hadn't been heard of B. hasn't been heard of C. hasn't heard of D. hadn't heard of

18. The library needs ______ but it'll have to wait until Sunday.

A. cleaning B. be cleaned C. clean D. being cleaned

19.Tom ______ to watch TV if he finished his homework.

A. allows B. allowed C. has been allowed D. will be allowed

20.Is this research center______ you visited the modern equipment last year?

A. where B. the one where C. the one that D. that