----What did Bob ask you just now?

----He wanted to know how long __________when I reached the cinema.

A．had the film been on

B．the film had started

C．the film had been on

D．had the film ended

超薄切片技术的步骤为（）

A.取材、固定、脱水、包埋、切片、染色

B.取材、固定、脱水、浸透、包埋、切片、染色

C.取材、脱水、固定、包埋、切片、染色

D.取材、固定、脱水、浸透、包埋、切片

E.取材、脱水、固定、包埋、切片