－Have you finished _______ your composition? It is time to hand it in.

－Not yet, I _______ it the whole morning, but it is so hard that I only finished half of it.

A．writing; had written

B．write; wrote

C．written; was written

D．writing; have been writing

位于内耳的是

A．鼓室

B．咽鼓管

C．半规管

D．乳突窦

E．乳窦小房