`4.` They said to / told me (that) I taught them how to use computers twice a week.

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

`+)` Lùi thì: HTĐ `->` QKĐ

`+)` Đổi ngôi: you `->` I `;` us `->` them

Câu tường thuật - dạng câu kể 

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

S + said + (that) + S + V (lùi thì)

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HTĐ --> QKĐ

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Đáp án: They told me that I taught them how to use computers twice a week.

`color{orange}{~MiaMB~}`