使用显微镜时，“观察”操作步骤正确的是（　　）

①转动粗准焦螺旋，使镜筒缓缓下降，直到物镜接近玻片标本为止；②左眼向目镜内看，右眼睁开；

③把要观察的玻片标本放在载物台上，用压片夹夹往；④反方向转动粗准焦螺旋，使镜筒缓缓上升；

⑤略微转动细准焦螺旋．

A．④②⑤③①

B．③①②④⑤

C．③②①④⑤

D．④③②⑤①

The house was very quiet, () as it was on the side of a mountain.

A. isolated

B. being isolated

C. isolating

D. having been isolated