13. In most countries around the world, A to school B .
A. 1. children having to go 2. children must go
3. every child has been 4. every child must have been
B. 1. when they reach a certain age 2. as they are growing old enough
3. since they reached a certain age 4. if they are too old to learn
14. A public transport to the exhibition hall B a parking space there.
A. 1. John will make his decision in traveling on
2. John is deciding that he has to travel in
3. John decided to travel by
4. John’s decision for traveling with
B. 1. since it would be difficult to find 2. although it is difficult to find
3. whereas it was difficult finding 4. and it is difficult finding