$I.$ $....$

$2.$ Nam said that they were learning English then.

- S + said + (that) + S + V (Lùi thì).

- Hiện tại tiếp diễn → Quá khứ tiếp diễn.

$3.$ I prefer watching TV to reading books.

- prefer V-ing to V-ing.

$4.$ This school was built 30 years ago.

- S + was/ were + V (Pii) + (by O).

$5.$ He has no intention of stopping working when he is 65.

$6.$ Ba has learned English since 2013.

- S + have/ has + V3.

- since + mốc thời gian.

$7.$ They said that hey were learning English then.

- S + said + (that) + S + V (Lùi thì).

- Hiện tại tiếp diễn → Quá khứ tiếp diễn.

$8.$ I prefer watching TV to reading books.

$9.$ This school was built 30 years ago.

$II.$ $....$

$3.$ The doctor warned not to smoke because it is very dangerous.

- S + warned + O + (not) + to V.

$4.$ Peter isn't giving the effort to solve his financial problems.

$5.$ Who put you in touch with me?

- put in touch (v.): sắp xếp cho ai để nói chuyện với ai.