in his studies he didn't know that all the others had left.A. BuriedB. BuryingC. Having

问题补充：

in his studies, he didn know that all the others had left.

A. Buried

B. Burying

C. Having buried

D. Bury

答案：

(答案→)A. Buried

B. Burying

C. Having buried

D. Bury

解析：考察形容词用法。本题中含有固定搭配be buried in…专心致志于…；这里的形容词buried是由动词bury转换的形容词。本句中的形容词短语buried in…是对句中主语he的情况进行的说明。句意：专心于学习，他不知道其他人都已经离开了。故A正确。