地球上纬度相同的各地（　　）

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   Most schools are trying hard to improve their lunch programs and they want to offer the best food they can.
   Even if your school provides healthy options(选择)，you may still want to have something delicious outside.How do you take control? Take a packed lunch to school!
   Here are the four reasons to pack your lunch and snacks at least twice a week.Control  Have you ever waited in the lunch line only to find when you get to the front that you don’t like what they’re serving?
   Variety  If you’re eating the same food all the time , your body probably feels ready for a change. Packing lunch a couple of times a week means you can enjoy some favorites that you might not find at every school.
   Money Serving Packing healthy snacks so that you needn’t go out for a fast-food lunch, chocolate or a soda! If so, you will save much money. And you can buy something you need.
   Warm Feeling   Remember when your mom or dad used to pack your lunch? Pack a lunch for yourself, maybe that is your favorite healthy food.
   Whether you pack or eat in the cafeteria(自助食堂)，what’s important is that you make right choices. If you are worried that cafeteria doesn’t offer enough healthy choices, try to make changes. Ask a teacher or someone in food service for advice on hoe to get started.
Take a packed lunch to school

Today is Monday. Tomorrow(明天) is ______.     

已知镁可以在某种气体中燃烧，用化学方程式表达为：2Mg+X2MgO+C，则X的化学式为____ ；该反应属于四种基本反应类型中的____ 反应．标出氧化镁中镁元素的化合价____ ．