—_____ does he like koalas?

—Because _____ are very interesting.                     [ ]

A. Why; it

B. What ; it

C. What ; they

D. Why; they

植物细胞及整株植物在生长过程中，生长速率变化的规律是（）生长.

A.慢—快—慢

B.缓慢

C.迅速

D.快—慢—快