Towards ___________ morning, _________ heavy snow began to fall.
| A．the... a | B．an... a | C．a...不填 | D．不填...the |
A cook will be immediately fired if he is found _______ in the kitchen.
| A．smoke | B．smoking | C．to smoke | D．smoked |
It is said that in Australia there is more land than the government knows _______.
| A．it what to do with | B．what to do it with |
| C．what to do with it | D．to do what with it |
The research is so designed that once _______ nothing can be done to change it.
| A．begins | B．having begun | C．beginning | D．begun |
Having a trip abroad is certainly good for the old couple, but it remains _______ whether they will enjoy it.
| A．to see | B．to be seen | C．seeing | D．seen |
_______ such heavy pollution already, it may now be too late to clean up the river.
| A．Having suffered | B．Suffering | C．To suffer | D．Suffered |