A:火箭点火发射
B:棉布制成衣服
C:石蜡加热熔化
D:水果榨成果汁
已知函数f(x)=2x3x<0-tanx0≤x<π2,则f(f(π4))=( )
⑴Bob is a good football player. ____
⑵Last Saturday, my father and I watched a basketball game.____
⑶This is our team.____
⑷—Who won? ____
—Tom's team won.
⑸My brother is a policeman.____
A. B. C.
D. E.
图为北美液地形略图.读图,完成下题.
如图是帮助我们理解生物学概念的有效方法,图中的①和②分别表示细胞的哪个生理过程?( )