Dear Jack,

    Can you believe I'm in a school of 2030 now? The school is like a beautiful garden. The wall of our classroom is colorful. Our school life is interesting.

    In the morning, we have three classes. We study on the Internet. We use the e-books. The teachers are all robots. They are in different rooms and they can answer any questions. Our robot music teacher plays the guitar very well. In the afternoon, we take a plane to the Mars to have two classes. I make friends with aliens(外星人). They are friendly and know us well. After class, we play soccer with them. Then we go back to the earth. Don't you think the life in this school is very interesting?

Mary

①我国居民的恩格尔系数在降低        ②收入水平对消费有直接的影响

③国外商品的价格比国内的便宜        ④人们消费行为受消费心理影响

可逆反应A（g）+ 2B（g）2C（g）的V—t图像如下左图，若其他条件都不变，只是在反应前加入合适的催化剂，则其V—t图像如下右图。

①a₁＞a₂  ②a₁＜a₂ ③b₁＞b₂ ④b₁＜b₂ ⑤t₁＞t₂  ⑥t₁＝t₂  ⑦两图中阴影部分面积相等 ⑧右图阴影部分面积更大，以上说法正确的是（      ）