The new system needs to be in operation for five months ________ it can be updated.
| A．as | B．while |
| C．before | D．once |
I am willing to do whatever my country requires __________ me.
| A．on |
| B．for |
| C．of |
| D．to |
You'll find it hard to get rid of the drug habit _______ you have it.
| A．before |
| B．once |
| C．until |
| D．though |
— The weather is changeable here. Please take more clothes.
—_____________.
| A．Well, it depends |
| B．Thanks, by no means |
| C．OK, just in case |
| D．Don't worry |
We can no longer ________ to consider water an almost free resource that we can use as we like.
| A．permit |
| B．afford |
| C．expect |
| D．spare |
He doesn't spend any more money on clothing than I do, but ________ he manages to look so stylish.
| A．therefore |
| B．somehow |
| C．furthermore |
| D．otherwise |