there was no hard evidence, most people thought he had broken the window of the classroom.
| A．While | B．Because |
| C．Unless | D．When |
I had just started back for the house to change my clothes _____I heard my name called.
| A．as | B．for | C．while | D．when |
It is an interesting story and one can't put it down _____ one has finished reading it.
| A．after | B．when | C．since | D．until |
I have been keeping the portrait _____ I can see it every day, as it always reminds me of my childhood in Paris.
| A．since | B．where | C．as | D．if |
_____earth scientists understand how and why earthquakes happen, forecasts are usually inaccurate.
| A．As | B．While | C．Because | D．If |
Mr. Smith wanted to buy the house and he told me that ____the house cost，it would be worth it.
| A．however | B．how much | C．whatever | D．what |