People didn’t use to produced as much rubbish as we do now.
A. use

B. produced
C. as much
D. do

`to` produce

vì used to+ V-inf
_________________
 Critics say Night at the museum is a must-see because of it is funny and exciting.
A. say
B. must-see
C. because of
D. exciting

`to` because

vì because+ clause

_______________
The public transportation is _________ than driving a car.
A. safe and fast
B. the safest and fastest
C. safer and faster
D. the safe and fast

vì có than thì thêm er vào tính từ ngắn 

B. produced `=>` produce

vì có used to+ V(nguyên thể)

_________________

C. because of `=>` because

vì because+ clause còn because of+ Noun phrase/ V-ing.

_______________

C. safer and faster

vì trong câu có than thì ta chia theo cấu trúc SSH: S1+ be+ adj-er+ than+ S2