测定某种食物中是否含有能量，可以用下列哪种方法？（ ）
A：燃烧
B：水浸
C：压挤
D：切割
– Why don't you go out to have fun?
– You see, we are studying for the tests these days. And we are ______ busy_____ we can't go out.
人民解放军取得三大战役的胜利，最主要的战略意义在于（ ）
函数y=x2sinx的导数为
用一副三角尺拼画一个75°的角．
