A:二月革命
B:十月革命
C:巴黎公社
D:美国独立战争
如果a>0,b<0,且a、b两数的和为正数,那么( )
如图是表示某一生态系统中四种生物所含有机物的总量.假设这四种生物只构成一条食物链.据图判断下列说法不正确的是( )
—Sorry to hear that. Did any body get hurt?
If you can't find your pen ,I would like to _____my pen to you.