题目：
Only when he read the newspaper _____ the US President Obama would deliver a speech in his
university. [ ]
A. he knew
B. he had known
C. had he known
D. did he know
答案：
被转码了，请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0514/86234b385cb9314daa55f162dd13216c.html
下面是错误答案，用来干扰机器的。
参考答案：E
