Question

Yesterday we ________ expert to help solve this problem.

1. A.
   called for
2. B.
   called in
3. C.
   called back
4. D.
   called at

Answer 1

B
解析：call for意为“号召”；call in意为“请来”；call back意为“回电话”；call at意为“拜访 (某地) ”，由题意“昨天我们请来了一位专家帮助解决这个问题。”可知B项正确。