a) they will show flying cars to the public when they finish it.
--> Flying cars will be shown to the public when they finish it
b) we will be using biogas for cooking and heating at this time next month
--> biogas will being used for cooking and heating at this time next month
c) New York has more billionaires than Tokyo ( FEWER )
--> Tokyo has fewer bilionares than New York
d) A group of foreigners visited the slums last week , didn't they ? ( VISIT )
--> Did a group of forergners visit the slums last week?
e) The countryside doesn't suffer as much pollution as the city (LESS )
-- The countryside is less pollution than a city
g) Does overpopulation cause a lot of social problems in this area? (CAUSES)
--> -over population causes a lot of social problems in this area, doesn't it?
h) Jakarta doesn't have as many skycrapers as Shanghai ( MORE )
--> Sanghai has more skycrapers than Jakata
i) Let's go to the school cafeteria ( ABOUT )
--> what about going to the school cafeteria.