1986年与1952年相比，我国劳动者增加了多少人（）
A．3.13亿
B．5.13亿
C．3.06亿
D．2.07亿
参考答案：C
It ________ nearly two weeks ______ I had received his letter.
A．is, that
B．was, that
C．is since
D．was, since
