____Six.

____I have computer class, PE and science.

____How many classes do you have on Wednesdays?

____Is it Wednesday today?

____What do you have in the afternoon?

____Yes, it is.

实数﹣2，0.3，$\frac{1}{7}$，$\sqrt{2}$，﹣π中，无理数的个数是（　　）

草履虫属于动物，而玉米属于植物，其主要依据是
①草履虫细胞结构没有细胞壁             ②草履虫能自由运动
③草履虫体内没有叶绿素，不能制造有机物 　④草履虫对外界刺激的反应很灵敏