`1`. People in this city used to travel by horse and cart.

`-` Chỉ thói quen trong QK: used+ to V: trước đây thường làm gì

`3`. What's the speed of airships`?`

`-` How fast `=` What is the speed of+ sth`?`

`4`. The subway is a good means of transport to help solve traffic problems in this city.

`-` a/ an+ adj+ N

`5`. John and Helen are used to travelling long distances.

`-` Chỉ thói quen ở ht: be/ get+ used+ to Ving: quen làm gì

`6`. You mustn't use the calculators in the exam room.

`-` mustn't+ V: cấm làm gì

`7`. Mary and Tom used to go swimming every day some years ago.

`-` giải thích giống câu `1`