问题
选择题
By improving reading skills, you can read faster and understand more of ________you once thought impossible to understand.
A．that
B．whether
C．which
D．what
答案
答案：D
通过提高阅读技巧，你会读得更快而且更多理解你曾经认为不可能理解的东西。Of后是宾语从句缺少宾语，think sth impossible.