不孕症是指育龄夫妇性生活正常，同居，未避孕，几年未妊娠
A．1.5年B．2年C．1年D．0.5年E．3年
参考答案：B
— According to my grandma, it is a good idea to eat chicken soup when you have a cold.
— _____, scientists agree with her.[ ]
A. Sooner or later
B. Once in a while
C. To be exact
D. Believe it or not
倾斜长壁采煤法适于缓斜厚度3.5m以下煤层，倾角在（）以下采用此法开采效果较好。
A.12°
B.13°
C.14°
D.15°
