兴奋性是指可兴奋细胞对刺激产生什么的能力()
A.反应
B.反射
C.兴奋
D.抑制
E.适应
参考答案:C
It has been estimated that only 21 percent of______world's land surface can be cultivated and that only 7.6 percent is actually under______cultivation.
A./.../
B.the...the
C./...the
D.the.../
专家建议的产妇开奶时间应该为()。
A.产后24h
B.产后12h
C.产后6h
D.产后3h
E.根据产妇情况尽量早