16. The lecturer had been speaking ____ an hour, and only then she stopped _____ a glass of water.
A since, have C for, to have
B at, had D in, having
17. Nick and I are good friends. We ____ each other for 5 years. We met when we ___ at school.
A know, were C have known, were
B knew, have been D known, been
18. I _____ Political science for five years. This is my___ year.
A studied, end C studying, last
B study, latest D have been studying, final