有4名学生A、B、C、D平均分乘两辆车，则“A，B两人恰好在同一辆车”的概率为____．

公元1世纪，东汉王充《论衡·乱龙》中记录了“顿牟掇芥”。顿牟即琥珀（也有玳瑁的甲壳之说），芥指芥菜子，统喻干草、纸等的微小屑末。这个词的意思就是经过摩擦的琥珀能吸引干草、纸等轻小的物体。下列关于这个现象的解释正确的是（   ）

用分子的性质解释下列生活中的现象，其中不正确的是（   ）

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.

下列有关物理现象的表述错误的是（  ）