第30题: [单项选择]The teacher was busy ______ sums upon the blackboard. She was too busy ______ the students' questions. A. to write out; answering B. to write out; to answer C. writing out; to answer D. writing out; answering 参考答案:C 答案解析:本题为句型搭配。be busy doing something 意为“忙于做某事”;too busy to do something 意为“太忙碌以至于不能做某事”。本题大意为:老师忙着在黑板上写算术