南美洲和北美洲的分界线是（ ） A．白令海峡； B.巴拿马运河； C.苏伊士运河； D.黑海；
(文)方程logam＜logan＜0(0＜a＜1),则下列结果正确的是A.1＞m＞n＞0 B.m＞n＞1C.0＜m＜n＜1
It ______ to my brother to write me if he ______ in a place where there were no phones.（ ） A. might never have occurred; was not B. might never occur; is not C. had never have o
取两支试管，分别加入一定量的Na2CO3和NaHCO3固体，加水溶解，然后向溶液中分别滴加稀盐酸，分析该过程中可能产生的现象，并写出所发生反应的化学
The new stadium being built for the next Asian Games will be __________ the present one. A. as three times big as B. three times as big as C. as big as three times D. as big three t
已知圆C与y轴相切，圆心C在直线x-3y=0上，且被直线y=x截得弦长为，求圆C的方程.
某研究小组的同学在探究酵母菌的细胞生理活动时，收集了酵母菌生长增殖的资料，参考如下图所示的实验装置进行了相关实验（CO2可使溴麝香草酚蓝
《墨子·告子》载：“诸侯朝天子曰述职。一不朝，则贬其爵；再不朝，则削其地；三不朝，则六师移之。”这段材料反映的历史现象是
