1. quang said:'' new pipes are very expensive '' ( use reported speech )
=> quang said that new pipes was very expensive
2. viet nam is a country that exports rice.( use compound worl )
=> viet nam is an rice exported country
3. the children love santa claus( use passive voice )
=> santa claus is love by the children
4. she asked nam:'' do you know great wall of china? '' ( use reported speech )
=> she asked nam if he knew the great wall of china

1.Quang said the new pipes were very expensive 

2.Viet Nam is a rice exported country 

3.Santa claus is loved by the children 

4.She asked Nam if he knew Great Wall of China 

Chúc bạn học tốt!