1. So sánh gấp bội (Multiple numbers comparison):

Cấu trúc:    S1 + V + multiple numbers (or times) + as + much/many/adj/adv + (N) + as + S2 + (C).

ex: - Mary types twice as fast as I do.

      - If I had not spent too much money, I would be twice as rich as Bill Gates.

      - I like to have televisions twice as many as computers.

      - The bicycle cost three times as much as the other one.

      - Their house is about three times as big as ours is.

      - Petrol is twice as expensive as it was a few years ago.

Lưu ý 1: Multiple numbers (or times) ở đây là: half, twice = two times, three times, four times,...

Lưu ý 2: Twice that much và twice that many có nghĩa là gấp đôi ngần ấy... và chỉ được sử dụng trong văn nói, không được dùng trog văn viết.

ex: We have expected 80 people at that rally, but twice that many showned up.

2. So sánh kép (Double comparison):

Cấu trúc 1:

The + comparative(1) + S + V, the + comparative(2) + S + V.

ex: The sooner you take your medicine, the better you will feel.

Lưu ý: Trong cấu trúc này, comparative(1) có thể khác cũng có thể giống comparative(2).

Cấu trúc 2:

The more + S + V, the comparative + S + V.

ex: The more you study, the smater you will become.

Cấu trúc 3: Đối với cùng một tính từ.

- Tính từ ngắn:

Ex: The weather gets cooler and cooler.

- Tính từ dài:

Ex: She grows more and more beautiful.

3. So sánh hơn kém không dùng "than":

- Có từ the trước tính từ hoặc trạng từ so sánh.

- Thường đi với cum từ Of the two + N.

Ex:

- Harvey is the smarter of the two boys.

- Of the two books, this one is more intersting.