3道英文题.说下答案和原因5,you can change money at the_____ bank at the

3道英文题.说下答案和原因
5,you can change money at the_____ bank at the airport.(change)
6,with the ropld population _____ more land is needed.(grow)
7,All the people at conferce are _____.
A,mathematic teachers B,mathematics teacher
C,mathematics teacher D,mathematic”s teachers