was known to them that the boss had broken his promise he would give them a rise.A. Wha

问题补充：

was known to them that the boss had broken his promise he would give them a rise.

A. What; what

B. It; which

C. It; that

D. As; that

答案：

A. What; what

B. It; which

(答案→)C. It; that

D. As; that

解析：C句意：他们都知道老板已经违背了将给他们涨工资的诺言。第一空处，It作形式主语，指代真正的主语“that the boss had broken his promise...”。promise之后是其同位语从句，从句句意完整且不缺成分，所以填that。