A：鱼类
B：两栖类
C：爬行类
D：哺乳类
关于x的多项式x3+（m+1）x2+x+2没有二次项，则m的值是（ ）
下列有关动植物细胞的比较不正确的是（ ）
—Bill didn't go to school this morning, did he?
—_______. Though he was not feeling very well.
If you do things ________, usually you can't do them well.
