自测练习（七）301-350

301. It was about 600 years ago ______ the first clock with a face and an hour hand was made.

A. that B. until C. before D. when

302. It was only when I reread his poems recently ______ I began to appreciate their beauty.

A. until B. that C. these D. them

303. Was ______ that I saw last night at the concert?

A. it you B. not you C. you D. that yourself

304. ______ was in 1979 ______ I graduated from the university.

A. That ... that B. It ... that C. That ... when D. It ... when

305. It is these poisonous products _______ can cause the symptoms of the flu, such as headache and aching muscles.

A. who B. that C. how D. what

306. It was only at that moment ______ the important role she had played as wife and mother.

A. he realized B. that he realized C. did he realize D. realized he

307. It was the American ______ first produced plastics on a large scale during the 1860s.

A. where B. wh