It's tree planting time!

　　大家一起來(lái)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(qǐng)寫寫植樹對(duì)城市空氣的作用。