预防贫血病需适量补充的元素是( )
如图,⊙A 和⊙B内切,它们的半径分别为3和1,过A点作⊙B的切线,切点为C,则AC的长为( )
----The radio says that a new typhoon (台风) is coming.
---- Really, All the ____ (渔民)on the sea must come back.