——What does your mother do to keep healthy, Tim?
——She usually ____.
A：swim
B：swims
C：is swimming
D：to swim
洋葱鳞片叶内表皮细胞不含叶绿体．（判断对错）
bì pīn dù àn dǒng gāng
冈____ 懂____ 渡____ 蔽____ 案____ 拼____
____
