①△ABC中角A，B，C的对边分别是a，b，c，若a＞b，则cosA＜cosB，cos2A＜cos2B；

②a，b∈R，若a＞b，则a³＞b³；

③若a＜b，则 $\frac{b}{a}$ ＜ $\frac{b+x}{a+x}$ ；

④设等差数列{a_n}的前n项和为S_n，若S₂₀₁₆﹣S₁=1，则S₂₀₁₇＞1．

其中正确命题的序号是____．

家蚕是具有社会行为的典型动物。

    Having a cheetah （猎豹）as a pet in the house? Does it sound scary to you? But for a family in South Africa， one cheetah is treated as a VIP (Very Important Person) in the house. The big cheetah is named Jolie, after the film star Angelina Jolie____. She can often be found eating from the kitchen table, taking a short sleep on the sofa, or even sleeping on Lucy and Jeff's bed. The big cat also sleeps and plays with the Browns' other pet, the more usual one--- a sheepdog____

    Having a cheetah as a pet is unusual. Atfirst，Mrs.Brown wasn't willing to keep a cheetah as a pet. She said,''____. But we are now happy that we did it--- she is part of the family.''

    Just like her name, four-year-old Jolie has achieved a celebrity(名人) status（地位）in the Browns' hometown. Fans often come to take pictures of her____.

    However, a cheetah is always a cheetah____. '' She makes a lot of mess in the house, urinating （小便）everywhere and chewing everything. It's her wild instincts (天性), said Mrs. Brown. There must be some problems of having a cheetah as a pet in the house, but some unusual fun must also be waiting ahead.

A. Interestingly, Jolie enjoys all the special attention that is paid to her.

B. An impossible friendship has happened between these two animals.

C. Though Jolie is now a pet in the home, she still has some wild habits.

D. She is surely the VIP at Lucy and Jeff Brown's home.

E. I was really against the idea of getting a cheetah as a pet.

按要求作文。

      请以“我真幸运，能成为你（您）的           ”为标题，写一篇作文。

      要求：①“你”和“您”任选其一，然后在题目横线处处填上的词语，补充题目。②立意自定③文体自选，可以记叙经历，抒发感情，发表议论，展开想象等。④不少于500字，如写诗歌，不少于20行⑤文中不得出现真实的地名校名和人名。

从“跨越太平洋的握手”到“跨越太平洋的合作”，中美关系展现出广阔的发展前景和蓬勃的生命力．中美两国“跨越太平洋的握手”开始于（  ）