Beijing is much busier than Ho Chi Minh city

=> Ho Chi Minh city isnt __________________

People say that Ha Long Bay consists of about two thousand islands

=> It is _________________

Beijing is much busier than Ho Chi Minh city.

=> Ho Chi Minh city isn't as busy as Beijing.

So sánh bằng: S + to-be + as + adj + as + O 

People say that Ha Long Bay consists of about two thousand islands.

=> It is said that Ha Long Bay consists of about two thousand islands.

Chủ ngữ giả: It + be + believed/said/thought/… + that + ... 

`->` Ho Chi Minh City isn't as busy as Beijing

`=>` cấu trúc so sánh bằng: S1+V+as+Adj+as+S2

`=>` S+am/are/is+not+N/Adj

`->` It is said that Ha Long Bay cosists of about two thousands islands 

`=>` It is said that+S2+V2+Clause