He has already gone home. But before he left, he__________ all the mistakes in his translation.

A．had corrected

B．has corrected

C．corrected

D．would correct

兰科植物的花被片分内、外二轮，每轮三枚，内轮中的一枚特化，形态及分类学中称：（）。

A.下唇

B.蕊喙

C.唇瓣

D.合蕊柱