有读者问： 有一道改错题：
Sir Winston Churchill (A: was) British Prime Minister (B: from 1940 to 1945), (C: druing that time) he played a decisive role (D: in the conduct of) the Second World War.
答案是C错，应改为during which time。将C改成during which可以吗？
不可以。during which何指不清楚，during which time则很清楚。顺便提一下，如将during that time ...the Second World War变成一个独立句，其中的that就不必改为which了。
