题目

碱式碳酸镁在300℃分解的化学方程式是：Mg2(OH)2CO3△ 2MgO + X + CO2↑，生成物X的化学式是A．H2O          B．O2             C．H2            D．CH4  答案：A解析:根据：Mg2(OH)2CO3△ 2MgO + X + CO2↑，可知，每个X中含有2个氢原子和1个氧原子，是水故选A It’s fun to receive presents. It also feels good to give to others. So what’s the best way to budget(预算) your money, shop wisely and spend the least money if possible?Susan Beacham, from a company that teaches money-management skills to kids, gives us some good advice.“My first tip is to make a list and check it twice,” says Susan. She suggests that kids talk with their families about whom to include in their gift giving and how much to spend. Start by writing down names. Then put a dollar amount next to each name and add it up. Do you have enough money? If not, make changes. And don’t forget—not everyone needs a store-bought gift. Susan points out that some of the best presents are free. Add to your list the names of people you want to give gifts of “time and talent”.The best gifts don’t cost a thing. Kids can give “time or talent”, says Susan Beacham. Here are some of her top gift ideas.·For the elder members of your family, do something for them, such as cleaning houses and washing clothes.·For a friend, create a work of art, like a poem, a drawing or a necklace.·For teachers, write a note telling her how special she is to you.·For the people who live around you, show that you care by volunteering. Find out who needs your help and what you can do. Giving your time to help others may end up being the best gift of all!阅读以上信息，用恰当的词完成下面的短文，每空一词。It’s fun to receive and give presents. Shopping wisely can 1. some money. Susan Beacham 2. kids to make a list and check it first. And she also points out some best presents are the ones which are not 3. from shops. For parents, kids can do some 4. as gifts. For teachers, kids can write a note telling them how special they are. For friends, kids can give them something they themselves create. For people 5. around, kids can spend some time helping those in need which can be the best gift.