先化简，再求值：[（x﹣y）2+（x+y）（x﹣y）]÷2x，其中x=3，y=1．
解：原式=（x2﹣2xy+y2+x2﹣y2）÷2x
=（2x2﹣2xy）÷2x
=x﹣y，
则当x=3，y=1时，原式=3﹣1=2．
补全对话, 每空一句。
Doctor: Good morning! ____
Tom: Tom.
Doctor: ____
Tom: I'm not feeling well. I have a toothache and I can't eat anything.
Doctor: When did it start?
Tom: ____
Doctor: Let me examine you. Open your mouth and say "Ah", please.
Tom: Ah……Is it serious?
Doctor: ____ Just stop eating candies and take the medicine. You will feel better soon.
Tom: How often should I take the medicine?
Tom: Thank you.
关于地球公转的叙述，正确的是（ ）
新疆自古以来就是中国的领土。早在西汉时期，中央政府便设置西域都护，总管西域事务，标志新疆地区开始隶属中央政府的管辖。清朝乾隆时期管理新疆的措施是设置（ ）
