As soon as his teacher begins lecturing he begins to doze off not intentionally but .A.

问题补充：

As soon as his teacher begins lecturing, he begins to doze off, not intentionally but .

A. personally

B. randomly

C. habitually

D. unconditionally

答案：

A. personally

B. randomly

(答案→)C. habitually

D. unconditionally

解析：考察副词词义辨析。A就个人而言；B胡乱地；C习惯地；惯常地；D无条件地；句意：老师一开始上课，他就开始打瞌睡，这不是有意地，这是他习惯如此。根据句意说明c 正确。