`1` He said that he couldn't go out with me then, he was very busy.

`-` Tường thuật: S + said + (that) + S + V(lùi thì)

`-` can `->` could

`-` you `->` me

`-` now `->` then

`-` HTĐ `->` QKĐ

`2` If you don't listen carefully, you won't know what to do.

`-` Câu điều kiện loại `1`:

`->` If + S + V(HTĐ), S + will/can/may + V

`=>` Có thật ở hiện tại, tương lai.

`1.` He said to me he couldn't go out with me then, he was very busy.

`-` Câu tường thuật (Câu kể)

`+` S + said (to sb) + (that) + S + V(lùi thì) + ...

`-` can (not) `->` could (not)

`-` HTĐ (to be) `->` QKĐ (to be): S + was/were

`2.` If you listen carefully, you will know what to do.

`-` Câu điều kiện loại `1` (Có thể xảy ra ở hiện tại hoặc tương lai)

`+` If + S + V(s/es), S + will/can/may/.. + V