1, My mum is taking a train to the city centre at the moment.

- at the moment : lúc này -> Thì hiện tại tiếp diễn : S + am/is/are + V-ing

- take a train to somewhere : đi tàu đến đâu

2, They would like to swim in a lake.

- would like to do sth : muốn làm gì

- swim in somewhere : bơi ở trong đâu

3, Tom and Peter are riding bikes to the countryside now.

- now : bây giờ -> Thì hiện tại tiếp diễn

4, He is going to stay in the city these days.

- Thì tương lai gần : S + am/is/are + going to + V nguyên thể

- stay + giới từ + địa điểm : ở lại đâu

- in + (tên) thành phố

1.My mim is taking the train to the city centre at the moment

-> Thì HTTD : S + is / am / are + V-ing ( 1 , 3 )

=> He , She , It + is

-> DHNB : at the moment

2.They would like to swim in a lake

-> S + would like + to do sth

=> Muốn làm gì

-> swim + in somewhere : Bơi ở đâu

3.Tom and Peter are riding bikes to the countryside now

=> You , We , They + are

-> DHNB : now

4.He is going to stay in the city these days

-> Thì TLG : S + is / am / are + going to do sth

=> He , She , It + is

=> Dùng để diễn tả về dự định của ai đó trong Tương lai

\text{# TF}