Question

 Fred entered without knocking and, very out of breath, sank _______ a chair.

A. on          B. off         C. into              D. to

Answer

 C

考查动词与介词的搭配。“sink into sth”意思是“渗入，陷入，沉入；投入……”等意思，“sink into a chair”意思是“（一屁股）坐到椅子上”。其它搭配均不恰当。

sink into…是一个非常有用的搭配，可与很多名词连用，表示多种意思，如sink into one’s mind（教训等）铭记在某人心中，sink into the sea沉入海中，sink into a deep sleep沉睡。