—Look at the sky! What is it?—Oh! UFO is landing on the ground.A. AB. AnC. /D. The

问题补充：

—Look at the sky! What is it?

—Oh! UFO is landing on the ground.

A. A

B. An

C. /

D. The

答案：

(答案→)A. A

B. An

C. /

D. The

解析：根据语境可做ＵＦＯ是泛指，故用不定冠词，又因ＵＦＯ的首音素是辅音因素，故用Ａ，故选Ａ。