It's tree planting time!

　　大家一起來植樹！

　　Lingling remembers that it's tree planting this weekend.

　　玲玲記得這周的活動(dòng)是植樹。

　　Please write about the effect of tree planting on air in a city.

　　請寫寫植樹對城市空氣的作用。