16. He had already learned the news. I the trouble to phone him about it.A. needn't have

问题补充：

16. He had already learned the news. I the trouble to phone him about it.

A. needn have taken

B. could have taken

C. should have taken

D. mustn have taken

答案：

(答案→)A. needn have taken

B. could have taken

C. should have taken

D. mustn have taken

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