6.his friend asked him if how he went to the airport.

7.lan asked lien if how much that dress cost.

8.ba asked tam if how often she washed her clothes

9.phong asked thu if when her father would leave.

10.the librarian asked my teacher if how many books the student needed.

B) 

1.pig-racing is often held at a country fair for entertainment.

2.new york is the biggest city in the usa but not the capital.

3.english is an offical language malaysia , india and many other countries .

4.london is the capital of england ,whereas edinburgh is the capital of scotland.

5.the number of English speakers in the world is increasing fast.

6. lan said that holography would help us interact in real time.

7. dean wanted to know if aliens could communicate verbally

8.mark asked if aliens could smell others' happiness and fear.

9.trinh asked what Martians had to drink.

6)his friend asked him how he went to the airport.

7)lan asked lien how much that dress cost.

8)ba asked tam how often she washed her clothes

9)phong asked thu when her father would leave.

10)the librarian asked my teacher how many books the student needed.

B) 

2)new york is th4 biggest city in the usa but not yhe capital.

3)english is an offical language india,malaysia and many other countries .

4)london is the capital of england whereas edinburgh is the capital of scotland.

Còn câu 1 bn tham khảo bạn kia nhé!!