Which book is ____ (difficult), this one, that one or the third one?
下图为北半球示意图,若箭头表示洋流动力方向,则该洋流是( )
东北地区人数最多的少数民族是( )
爸爸参加“收获节”的目的( )。
There are lots of books in the library.(改为同义句)
____