a we encouraged to donate books and clothes to street children

-> cấu trúc : encouraged +  to V

b what  can we do to help clean the environment?

-> cấu trúc : what can + S + do / does + to V

c have you ever done any volunteer work ?

-> thì HTHT + ever : have / has + S +VPII 

-> any đi với câu nghi vấn 

d joe spent most of his free time doing volunteer work at a local hospital

-> spent / spend time + V-ing

e they estabilished the first univeristy in VN many years ago 

d big flood has caused a lot of damage to the village where my home recently

-> thì HTHT : s +have / has + VPII

$-$ We encouraged people to donate books and clothes to street children .

Trong câu này ta có cấu trúc câu : " S + encouraged + O + to + V "

$-$ What can we do to help clean the environment ?

Trong câu này ta có cấu trúc câu  : " What can + S + do  + to V + O ... ?  "

$-$ Have you ever done any volunteer work ?

Trong câu này ta có cấu trúc ở thì hiện tại hoàn thành : " Have/Has + S + PII ? "

$-$ Joe spent most of his free time doing volunteer work at a local hospital .

Trong câu này ta có cụm từ cố định : " spent / spend time + V-ing "

$-$ They estabilished the first univeristy in Vietnam many years ago .

Câu này sắp xếp theo nghĩa 

$-$ Big flood has caused a lot of damage to the village where my home recently . 

Trong câu này ta có cấu trúc ở thì hiện tại hoàn thành : " S + have/ has + PII "