清除异物：地毯上落下些绒毛、纸屑等质量轻的物质，（）就可以解决。
参考答案：吸尘器
电镜结构常用的计量单位是（）。
A、cm
B、mm
C、μm
D、nm
E、A°
— Could you tell me __________________? — Next Sunday.
A．when they would go there
B．where they will do
C．when they will come here
D．who they would meet
