问题
选择题
18. It was because of English girlfriend, believe it or not, ______ his English improved so greatly.
A．which
B．as
C．that
D．what
答案
答案：C
为强调句型，被强调成分为 because of English girlfriend。由于句中插入了believe it or not这一成分，致使许多同学误认为这是一个非限制性定语从句。