— ________ is the book sale?
— It's next week.
A:What
B:Who
C:Where
D:When
臭氧层是地球的保护伞,臭氧(O3)属于( )
如图曲线表示食物通过人体消化道时,淀粉、脂肪、蛋白质被消化的程度,字母代表组成消化道的各器官及排列顺序.据图回答