Peter hurried through dinner, changed into old clothes, _______ in the lab for three hours.

A．worked

B．working

C．and worked

D．to work

下面有关显微镜的叙述错误的是（　　）

A．高倍镜换上低倍镜后视野变暗，观察到的细胞数目增多

B．观察到的物像在视野的右上方，使物像移到视野的正中央，应向右上方移动装片

C．对光时光线太弱应选用凹面镜、大光圈

D．如果视野中物像模糊不清，可以转动细准焦螺旋使像清晰