4. I suggest helping street children by giving them lessons on the weekend.
-> suggest doing sth: đề nghị làm gì
5. Shall we take part in voluntary work in our community?
-> Shall we + V-bare?
= How about + V-ing?
6. Let's go to the canteen for a drink.
-> Shall we + V-bare?
= Let's + V-bare: hãy làm gì
7. Why don't we practice speaking English every day?
-> Why don't + we/you + V-bare?
= What about + V-ing?
