下图表示一个细胞进行分裂的过程中，细胞核内染色体数目以及染色体上DNA分子数目的变化情况。下列叙述中，正确的一组是（）

①实线和虚线分别表示染色体数和DNA分子数的变化 ②两条曲线重叠的各段，每条染色体都含有一个DNA分子 ③在MN段，每个细胞内都含有和体细胞相同数目的DNA ④在IJ段，可发生同源染色体的交叉互换，同源染色体的分离和非同源染色体的自由组合 

可以适当增加细节，以使行文连贯，字数100左右。

Dear Tom,

    I'm so happy to write to tell you something about my new English teacher, Miss Lin.

    Look  forward to your early reply.

Yours,

Li Hua

  Karl was at home with his brother Michael and his sister Addy．As he ____(推)the window open, he saw a big panda in the backyard．He ____(大喊)to Michael．Michael ____(回答)that pandas should be in the ____(森林)．Then they went out, the panda was already there talking to Addy．The panda said he was sorry that he flew here with his umbrella ____(没有)____(敲门)on the____(门)．The next day, Addy walked____(往)the panda's house with a gift．In ____(返回), the panda told Addy a story  ____(在……上面)a tree．And the panda also told Karl another story after they played games．That's the story in the book Zen Shorts．

函数$f\left(x\right)=\frac{1}{2}{x}^2+1\left(x<-2\right)$的反函数是（  ）

观察下列蛋白质合成示意图，回答问题：（注：甲为甲硫氨酸，丙为丙氨酸）