$1. $ There are twenty classrooms in my school

$→$ S + have/has + N

$→$ There are + số lượng + N(đếm được số nhiều) + ......

$2. $ Mount Everest is the highest mountain in the world

$→$ So sánh nhất với tính từ ngắn : S + to be + the + adj + est + Noun/ Pronoun

$3. $ The house is behind the tree

$→$ In front of >< Behind : Trước >< sau

$4. $ A car is more expensive than a motorbike

$→$ So sánh hơn với tính từ dài : S + to be + more + adj + than + Noun/ Pronoun

$5. $ Our garden hasn't many flowers

$→$ S + have/has + (not) + N

`@Chamian`

=>
1. There are twenty classrooms in my school.
-> there are + N số nhiều (~ have)
2. Mount Everest is the highest mountain in the world.
-> so sánh nhất the adj-est 
3. The house is behind the tree.
-> behind : phía sau, ở đằng sau
4. A car is often more expensive than a motorbike.
-> so sánh hơn more adj than
5. Our garden doesn't have many flowers.
-> have/has : có