发动机是将某一种形式的能量转变为（）的机器。A.电能 B.机械能 C.热能 D.化学

-There is a mobile phone on the desk. Is it Li Yong's?

-It __________ Li Yong's. He went to Shanghai two days ago.[ ]

A. can be

B. can't be

C. must be

D. might be

与B细胞淋巴瘤和鼻咽癌有关（）

A.EB病毒

B.人 * * 瘤病毒

C.人嗜FT淋巴细胞病毒

D.甲胎蛋白

E.癌胚抗原

It was not until he arrived at the office_____ realized he had forgotten the key.

A．and he

B．when he

C．that he

D．he