用下列物质填空：氢气、一氧化碳、氧气、二氧化碳、活性炭，并写出有关反应的化学方程式．

(2011年新疆塔城质检) 完全相同的甲、乙两个物体放在同一水平地面上，分别在水平拉力F₁、F₂作用下，由静止开始做匀加速直线运动，分别经过时间t₀和4t₀，速度分别达到2v₀和v₀时撤去F₁、F₂，甲、乙两物体开始做匀减速直线运动，直到静止．其速度随时间变化情况如图1－3－9所示，则下列各项说法中不正确的是(　　)

图1－3－9

为灾区儿童捐款，小华捐了19元，小丽捐了28元，她们共捐的钱数(      )

They walked into the classroom one _____ one.

完形填空。
    Hello. I'm Jenny. I have a best friend.   1 name is Amy. We are in the same school. We both can sing and dance well. She is as  2 as me.
    At school, my teachers all can make 3   happy. But we must4  white blouse with the long sleeves. I am good 5   maths and English. She 6  English. She thinks it's difficult. Yesterday we7   a party at school. We enjoyed ourselves.
    At spare time, my favourite8   is winter. I like 9  snowmen in winter. But she likes eating ice creams in summer. What a pity!
    In two months' time, we are going to go to middle school. We are very busy every day. We  10   harder than now.