---_______ one and a half months enough for the project to be finished?

　　---I am afraid not. The professor is ill and only after he recovers ________ go on with it.

A．Is; he can

B．Are; he can

C．Is; can he

D．Are; can he

关于湄公河，恒河，尼罗河三角州的叙述，正确的是（）

A.按经度由低到高排列，恒河三角洲，湄公河三角洲；尼罗河三角州

B.都受副热带高压的控制或影响

C.粮食作物都是水稻和小麦

D.三角洲上都有国家首都