问题
选择题
______ halfway through the exercise, the teacher changed his mind and collected all our papers.
A．When only being
B．When we were only
C．Being only
D．Having been
答案
答案：B
我们只做了一半练习老师就改变了主意把我们的试卷收了上去。因为主句与从句的主语不一致所以不能用分词做状语故选B