—How long do you suppose it is he arrived here?
—No more than half a week.
| A．since | B．before | C．that | D．when |
Lawrence Craven, a doctor from the US, introduced the idea in 1953 _______ aspirin has the potential to reduce the risk of heart attacks.
| A．that | B．when | C．which | D．why |
Keeping on doing good deeds brings us peace of mind, ________ is important for our happiness.
| A．which | B．that | C．what | D．it |
_______ I have never thought of getting a job in such a big company, I’ll have a go at it.
| A．Since | B．Unless | C．Once | D．While |
Not only _______ many people’s lives by reducing fever and helping stop pain, but there are also other things that aspirin can help with.
| A．has aspirin saved | B．has saved aspirin |
| C．aspirin has saved | D．saved aspirin has |
It is vital that every piece of equipment ________ checked before the experiment.
| A．would be | B．must be |
| C．should be | D．might be |