we went to visit Professor Smith, he his research work.
A. The first time; devoted to
B. Whenever; was concentrate on
C. For the first time; was busy with
D. Each time; was absorbed in
网友回答
A. The first time; devoted to
B. Whenever; was concentrate on
C. For the first time; was busy with
(答案→)D. Each time; was absorbed in
解析：Each time每次；The first time第一次；Whenever无论何时；逗号前后都是一个句子，故第一空应选连词，所以排除C，devote to致力于；concentrate on集中精力于；be busy with忙于；be absorbed in专心于。句意：每次我们去看望史密斯教授时，他都在专心于他的研究工作。