A:2
B:-2
C:
D:
⑴____ A. cousin B. sister C. Miss D. nurse
⑵____ A. there B. here C. where D. bear
⑶____ A. tall B. ball C. also D. all
⑷____ A. this B. thin C. there D. they
⑸____ A. uncle B. orange C. student D. stand
如图,点C在⊙O的直径BA的延长线上,AB=2AC,CD切⊙O于点D,连接CD,OD.
(1)求角C的正切值:
(2)若⊙O的半径r=2,求BD的长度.
结合下图说出影响乞力马扎罗山植被垂直分布的主要原因( )