病毒寄生在活细胞里，利用该细胞内的物质和遗传信息繁殖后代．（判断对错）

在一定温度下，向一个2L的真空密闭容器中（预先装入催化剂）通入1molN₂和3molH₂，经过一段时间后，测得容器内压强是起始时的0.9倍．在此时间内H₂的平均反应速率为 0.1mol•L^﹣1•min¹，则经过时间为（　　）

根据短文理解, 从A、B、C三个选项中选择最佳答案填空。

    Have you ever planted a few trees on Tree Planting Day? Each year, millions of people, both 1, plant a lot of trees. But this may not be the best way to make your home 2.

    Last week we visited a park in Hebei. We were  3 to find most of the trees had been burned. The workers told us that the trees  4 soon after they were planted because they weren't watered well enough. 5 workers burned them and cleaned the place for 6 trees to be planted this year. 7 a card found in one of the dead trees, a student wrote, "I hope this tree will grow up with me to  8 the backbone(栋梁) of our country." The workers said that the survival(存活) of the trees was really more important than 9 trees were planted.

    Some people in Beijing now have a new idea that they can donate(捐赠) some money and let professional (专业人士) plant and 10  the trees.

① $\frac{7}{9}$ ÷ $\frac{11}{5}$ + $\frac{2}{9}$ × $\frac{5}{11}$

②（1- $\frac{1}{2}$ - $\frac{5}{12}$ ）÷ $\frac{1}{4}$

③（ $\frac{1}{6}$ + $\frac{3}{4}$ - $\frac{2}{3}$ ）×12