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

问题补充：

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

答案：

(答案→)A. that

B. until

C. before

D. when

解析：考察句型。该句为强调句，强调句的特点是去掉It was ……that……以后句子结构完成。即，the first clock with a face and an hour hand was made about 600 years ago 句子结构完整。