$1.$ Now my brother feels worried because he is having a big assignment to complete.

- S + V (s/es).

- S + am/ is/ are + V-ing.

$2.$ In the past most girls liked to knit scarves and sweaters themselves.

- like + to V: thích làm gì.

- S + V (-ed/ bất quy tắc).

$========="$

$1.$ I have never read such an interesting book.

- S + have/ has + V3.

$2.$ He felt quite depressed about the visit to the gallery.

- S + V (-ed/ bất quy tắc).

$========="$

$1.$ The artisan moulded the copper so that they could make a bronze drum.

- so that + S + V: Vậy nên ...

- could + V (Bare).

$2.$  Although there are mordern knitting machines, the artisans in my village like using traditional looms.

- Although + S + V: mặc dù

- like + V-ing.

$3.$ Nguyen asked his teacher when she should start the computer.

- S + asked + O + wh- + S + V.

$========="$

$1.$ They said they wanted to send their son to a university in the UK.

- S + said + that + S + V (Lùi thì).

- want + to V: muốn làm gì.

- Thay đổi một số từ: our $→$ their ; we $→$ they.

$2.$ The teacher asked Ngoc if she had ever tried a calling a helpline.

- S + asked + O+ if + S + V (Lùi thì).

- Lùi 1 thì: Hiện tại hoàn thành $→$ Qúa khứ hoàn thành.

=>
I/
1. Now my brother feels very worried because he has a big assignment to complete.
-> feel adj : cảm thấy
-> to V : để làm gì
2. In the past, most of the girls liked knitting scarves and sweaters for themselves.
-> in the past (QKĐ, S V2/ed)/ like Ving : thích làm gì
II/
1. I have never read a more boring book than this one.
-> have/has never V3/ed
2. He felt quite depressed about the visit to the gallery.
-> feel adj : cảm thấy 
-> người (tính từ đuôi ed)
III/
1. The artisan moulded the copper so that he could make a bronze drum.
-> so that S V (chỉ mục đích : để)
2. Although there are modern knitting machines, the artisans in my village like using traditional looms.
-> although S V : mặc dù
3. Nguyen asked his teacher when to start the computer.
-> wh word to V ~ wh word S should V
IV/
1. They said that they wanted to send their son to a university in the UK.
-> câu tường thuật, lùi thì (HTĐ -> QKĐ)
2. The teacher asked Ngoc if she had ever tried calling a helpline.
-> câu tường thuật dạng Yes/No questions : asked sb if S V(lùi thì, HTHT -> QKHT)