— Do you know where David is? I couldn't find him anywhere.

— Well. He _____ have gone far-his coat is still here. [ ]

A. shouldn't

B. mustn't

C. can't

D. wouldn't

俗称“黄油”的润滑脂的含义是（）。

A.钠基润滑脂

B.钙基润滑脂

C.复合铝基润滑脂

D.锂基润滑脂