根据括号里所给的汉语写出英语单词。

1.Try to____ （步行)or ride a bike when you travel a short distance.

2.Chinese people usually eat ____  (月饼) on Mid-autumn Day.

3.It isn't ____  (容易的) to learn English well.

4.Do you want to____ (制作) cards by hand for your teachers on Teachers' Day?

5.Cars pollute the ____ (空气)，so remember: Use your legs

第一年因生源和环境等因素，全校总班级至少 $20$  个，至多 $30$  个，若每开设一个初、高中班，可分别获得年利润 $2$  万元、 $3$ 万元，则第一年利润最大为（   ）