宋太祖从地方军队中挑选精壮士兵编入禁军主要是为了（    ）

温度上升－3后，又下降2实际上就是 （     ）

阅读短文，判断正确还是错误。

A letter

Here is a letter from Jim to his friend in the USA

Dear Lily:

    I am in China now. I go to school five days a week. The school and the food are good here. I have some Chinese friends. They are all very friendly to me. On Saturdays and Sundays we stay at home. In the afternoon we play games. My Chinese friends like English very much. They ask me to teach them English and they teach me Chinese. I like staying here.

    Please write soon!

淀粉、脂肪和蛋白质在人体消化道内被消化液消化的先后顺序正确的是（   ）。

从一架钢琴挑出的十个音键中，分别选择3个，4个，5个，…，10个键同时按下，可发出和弦，若有一个音键不同，则发出不同的和弦，则这样的不同的和弦种数是（　　）