Due to the light pollution, stars are too faint _________with naked eyes in the urban area.
| A．observing | B．being observed |
| C．to be observed | D．to be observing |
The agent was about to sign his name to the document ________，to our surprise，a stranger broke in to prevent him.
| A．while | B．when |
| C．as | D．until |
Please arrange an interview with the manager tomorrow，or ________ it is convenient to him.
| A．whenever | B．however |
| C．whichever | D．wherever |
—What do you think of it?
—Well，it’s worth doing ________ the result is satisfactory.
| A．the moment | B．as soon as |
| C．once | D．so long as |
________，his idea was accepted by all the people at the meeting.
| A．Strange as might it sound |
| B．As it might sound strange |
| C．As strange it might sound |
| D．Strange as it might sound |
Bring the flowers into a warm room ________ they’ll soon open.
| A．or | B．and |
| C．but | D．for |