有一个电流表G，内阻R_g=30Ω，满偏电流I_g=1mA．要把它改装为量程0～0.6A的电流表，要并联多大的电阻？改装后电流表的内阻是多大？

“1640年革命和1789年革命，是欧洲范围内的革命。它们产生了欧洲社会的‘新政治制度’。”这里的“新政治制度”指的是（　　）

在“活性炭、碳酸钙、食醋、钛合金、聚乙烯、甲烷”中选择适当的物质填空：

完形填空
    My mother is a doctor.She is unable to get back home 1 every day.And she has to work on weekends sometimes.So it's hard for her to do all the 2 after work.
    As a member of the family，I think it's my duty to 3 some housework.4Mom always says she doesn't need any help，there are always things I can do.5 ， I can help do the dishes and set the table.I'm sure Mom loves me 6 to help her.
    What's more，I'm trying to be 7.I wash my own clothes，tidy up my bedroom and take care 8 my things.I'm old enough to do these things.And I can't9 on my parents forever.
    Always show your 10 to your mom for everything she does.I believe she will feel sweet.Try it now.

下列有关量的描述不正确的是（   ）