Answer: David told me that if he weren't busy, his sister would visit him the next Sunday morning.

`@` Câu trần thuật ~ gián tiếp:

`-` S + said/told/said to + (O) + (that) + S + V(lùi thì)

`-` Lùi thì: HTĐ `->` QKĐ

               will `->` would

`-` Đổi ngôi:

`+` I `->` he

`+` My `->` his

`-` Me `->` him

`-` Next Sunday morning `->` the next Sunday morning

Trans: David nói với tôi rằng nếu anh ấy không bận, chị gái của anh ấy sẽ đến thăm anh ấy vào sáng Chủ nhật tuần sau.

`answer:` David told me that if he was not busy, his sister would visit him the following sunday morning

`-` Câu gián tiếp dạng câu kể:
S + said to/ told + O + (that) + S + V(lùi thì)

`-` lùi thì: HTĐ `->` QKĐ; will `->` would.