句式与其他三句不同的一项是（  ）

从每小题所给的A、B、C三个选项中，选出可以填入空白处的最佳答案。

    It is the first day for school．All the students are1 in the classroom．Mrs．Green 2 and says，"Good morning，class．I'm your teacher．I'll teach you English，math and some 3 classes．If you have any questions (问题)，you can 4 me．I'm very glad to answer (回答) your questions．Boys and girls，from now on，you are school 5．You must study hard at school and help your parents at home．"

    A boy puts up6 hand and asks，"We'll do well in our lessons．We can be good students．But what can we do to 7 parents at home?"

    The teacher says，"Think it over and you'll 8 the answer．" "Who usually washes your clothes?"

    A girl stands up and says，"The washing machine (洗衣机)!"

    "Who often 9 for you?" asks the teacher．

    "The microwave oven (微波炉)，" says a tall boy．

    "Who uses them?" asks the teacher 10．

    "The electricity (电)!" all the students answer at the same time．

已知函数f（x）=x²+|x|﹣|x﹣5|+2．

There are lots of rules at Selina's school.
She agrees with some1them. For example, they can't arrive2 , they can't  run in the hallways, and they can't eat in class. All3 rules are okay because they're reasonable(合情合理的).
But there are some rules Selina4agree with. For example, at her school they have to wear a uniform and they can't wear jeans. But she thinks jeans are5because they're comfortable. In school, they can't listen to music in art class. Selina doesn't agree with this rule. She thinks 6 music in art crass is okay.
Selina7 has to follow some rules at home. For example,8she wants towatch TV, she has to finish her homework first. And she can't go out with her friends 9school nights, that is, from Monday to Friday, she also has to clean her room10week. Luckily, she doesn't have to take out the trash（垃圾）. She hates it.

小明用两个相同的滑轮，组成不同的滑轮组如图所示，分别将同一物体匀速提高到相同高度，绳子的自由端移动的距离为S₁、S₂，图中左右滑轮组的机械效率分别为η₁、η₂，下列关系正确的是（忽略绳重及摩擦）（  ）