`1` C

`->` d/c : "....so traffic in the city centre is heavier than that in the subburbs"

`2` A

`->` d/c : ".....but the Londoners prefer their own cars"

`3` B

`->` d/c : "At the weekends , the streets are noisier ang busier ......"

`4` D

`->` d/c : "Althought the living cost in the suburbs and the countryside is cheaper than in the city...."

`5` A

`->` d/c : "The public means of transport is cheaper than...."

$baoyen.$

`1. C`

`=>`  People go everywhere by car, so traffic in the city centre is heavier than that in the suburbs.

`2. A` 

`=>` The public means of transport is cheaper than cars but the Londoners prefer their own cars. 

`3. B` 

`=>` At weekends, the streets are noisier and busier 

`4. D`

`=>` Although the living cost in the suburbs and the countryside is cheaper than that in the city centre, most young people prefer living in the city centre.

`5. A`

`=>` The public means of transport is cheaper than cars but the Londoners prefer their own cars.