I don’t know . When he . I will phone you.
A. when will be some back, es back
B. when is he ing back, will e back
C. when he es back, is ing back
D. when he is ing back, es back
网友回答
A. when will be some back, es back
B. when is he ing back, will e back
C. when he es back, is ing back
(答案→)D. when he is ing back, es back
解析：此题重点考查when引导宾语从句和时间状语从句的不同。前者要用陈述句语序，且时态要和主句保持一致；后者常用一般现在时。