Strong __________ can be very dangerous for swimmers.
| A．flows | B．columns |
| C．floods | D．currents |
Great changes _________ in many fields since China was open to the whole world.
| A．have taken place | B．took place |
| C．have been taken place | D．were taking place |
_____you’ve made a promise, you are expected to carry it out.
| A．While | B．Unless |
| C．Once | D．Though |
His parents insisted that he __________English well when he was in junior school.
| A．would learn | B．must learn |
| C．learned | D．learn |
I don’t like this new model of App6 +; _________I had enough money, I wouldn’t buy it.
| A．only if | B．even if |
| C．as if | D．if only |
Your speech was heard by a group of five judges, _______ agreed that it was the best one this year.
| A．all of whom | B．all of who |
| C．all of them | D．all of those |