A:①②
B:①③
C:②④
D:③④
Can you see the boys football on the playground? They are my classmates.
设集合A=x|x≥1,B=x|y=log2x+2,则CBA=
蝗虫的若虫与成虫相比,本质的区别是( )
如图是某生态系统食物网简图,请仔细观察分析并回答下列有关问题.