问题补充:
The professor to walk out of the office when one of his students came in.
A. was about to
B. was going to
C. would
D. was to
答案:
(答案→)A. was about to
B. was going to
C. would
D. was to
解析:考察固定句式be about to,将要做某事。句意:当他的一位学生进来时,这位教授即将走出他的办公室。选项BCD缺少谓语动词,故选A。