`Answer + Explai n :`

`1.` No matter how hard I tried, I couldn't open the door.

`-` Try as hard as S `+` might : dù ai đó đã cố gắng

`=>` No matter how `+` Adj/Adv `+` S `+` V,… : Dù ai đó đã có cố gắng thế nào đi chăng nữa..

`2.` It's against the law to have two wives at the same time in my country.

`->` tobe against: chống lại

`3.` Had it not been for your lack of attention, you wouldn't be asking questions now.

`-` Đảo ngữ câu ĐK loại `3` :

`->` Had `+` S `+` (not) `+` been `+` `...` `+` S `+` would/might/could `+` have `+` P`2`

`4.` Big Ben is famous throughout the world.

`->` Famous throughout : nổi tiếng khắp nơi

1, No matter how hard I might try, I couldn't open the door

- No matter how adj S might V1, clause : Dù

2, It's against the law to have two wives at the same time 

- It's against the law to V1 : Trái với luật pháp

3, Had it not been for your inattention, you wouldn't be asking questions now

- Đảo ngữ ĐK hỗn hợp 2 và 3 : Had it not been for + V-ing/N, S + would + V1

4, Big Ben is famous around the world

- Famous around the world : Nổi tiếng trên toàn thế giới