如图所示的电路，水平放置的平行板电容器中有一个带电液滴正好处于静止状态，现将滑动变阻器的滑片P向左移动，则 (　　)

分类是学习和研究物质的一种常见的方法，下列物质的分类正确的是(    )

0.5÷0.9____0.5          

0.55×0.9____0.55

36÷0.01____3.6×100       

7.3÷0.3____73÷0.3．

用适当的介词填空

①As a student, you should focus ____ your school work rather than some other things.

②Working in so much noise can cause damage ____ your hearing.

③His laziness and carelessness led ____ his failure in the examination.

④I am still a little confused____ what happened.

⑤I don’t want to make comments  ____ other people’s privacy.