用所给词的适当形式填空
(1)What about ____ (eat) some fish for supper?
(2)Sam is an ____ (England) boy.
(3)He can finish ____ (read) the book this week.
(4)What ____ he often ____ (do) after school?
(5)This is my cat. Do you know ____ (it) name?
甲、乙两种固体物质的溶解度曲线如图所示,据图回答下列问题:
已知向量a→=(1,2),b→是单位向量,a→和b→的夹角是2π3,则b→在a→方向上的投影是( )