_______ a chance, we will visitEdinburgh a second time

It was the third time that I _____ to Beijing. [ ]

George is going to talk about the geography of his country, but I’d rather he _____ more on its culture. [ ]

derly need special care in winter, asthey are_____ to the sudden change of weather.

The flu is believed _____ by viruses that like to reproduce in the cells inside the human nose and throat.