山颠白雪皑皑、冰川广布的地形区是 （   ）

在﹣2，π，2x，x+1，$\frac{xy}{2}$中，代数式有（　　）

南繁是秋冬季节全国各地到海南从事农作物品种选育、种子生产和种植鉴定等活动;海南冬季瓜菜大量销往内地省市。读海南岛最冷月平均气温分布图，水稻、小麦、玉米发芽适宜温度表和海南冬季瓜菜内地主要省市供应量图，回答下列问题。

根据所给的语境和首字母的提示，补充完整下面的对话。

Nina: Can you d____sports with me this weekend, Andy?

 Andy: Sorry, I can't.

Nina: W____will you do this weekend?

Andy: I don’t know. My mom a____ comes home from work so tired. I w____to help her around the house. What chores can I do around the house for my mom?

Nana: Try this... make a list of (一列表) the chores your mom has to do when she comes home from work.

Andy: OK. She has to m____the bed. I will do it. She has to cook. I c____cook, but I will help her by washing the vegetables. She has to d____the dishes. She has to c____the floor, dust the furniture and w____the dog. I can do all of them.

Nana: You d____have to do all of the chores. You may help your mom by keeping your bedroom clean and tidy. 

Andy: I see.