右图是细胞免疫中x细胞与靶细胞密切接触后的杀伤作用过程示意图，其中x细胞是(      )

当地球运行到右图中四点时，公转速度由慢到快排序正确的是（   ）

下面最接近空调器的额定功率的是（  ）

    We spend hours, days and years of our lives in school. Imagine(想象) you could design(设计) your dream school, what would it be like? What would you be doing? We wanted to find out what teenagers around the world thought. Here is what they said:

    Richard from the USA: My dream school would have a big swimming pool and two soccer fields. It would also have a cinema, a gym and a shopping centre. My school has none of these, and I think there should be more pleasant things for students to do while they are studying.

    Sonia from Italy: I'd like a room where we can relax and play computer games. I'd also like to have a music room. I think there should be a place for everyone to go and relax after class.

    Wu from Beijing: I think it would be great to have another day off (休息日) every week, besides the weekend. If that day was a Friday or a Monday, we would have a long weekend every week. What fun! I also think school should start later, at about 10 o'clock, and finish earlier.

    Hannah from Australia: In my dream school, I think the teachers should give us more freedom(自由) and choice about how we study and what we study. I also think it's not necessary for us to wear school uniforms every day. I really don't like wearing it.