蓄电池组每年应做一次核对性放电试验，放出额容量的（）。A．50~60%  B．30~

This is the only way that I can think of _______ the problem of water waste in urban areas.

A．settling

B．to settle

C．settle

D．settled

为什么说绿色植物在碳循环中具有重要作用？

— Must I take my own sleeping bag for the camp?

— You _______.We have prepared one for each of you.

A．mustn’t

B．can’t

C．may not

D．don’t have to

属于配伍禁忌的是（）

A.人参与藜芦

B.人参与海藻

C.人参与大戟

D.人参与莱菔子

E.人参与五倍子