Đáp án:

`-` So `:` Vì vậy ; nên

`-` Cấu trúc `:` C1 + so + C2

 `->` Dùng để chỉ kết quả của một sự việc ; hành động ; sự kiện

`1.`  You are very young so you can't have a front `-` door key.

`2.`  It is very cold so we can't bathe.

`3.`  I am rather old so I can't wear that kind of hat.

`4.`  The ladder wasn't very long so it didn't reach the window.

`5.`  He hadn't much money so he couldn't live on it.

`6.`  He was furious so he couldn't speak.

`7.`  The fire isn't very hot so it won't boil a kettle.

`8.`  Tom was very foolish so he told lies to the police.

`9.`  You are quite thin so you could slip between the bars.