----The light in the office is still on.
----Oh, I forget ______.
| A．turning it off | B．to turn it off | C．turning off it | D．to turn off it |
_____, water can be changed into gas.
| A．Heated | B．Being heated |
| C．Having heated | D．Having been heated |
There is _____ what the weather will be like.
| A．not knowing | B．no knowing | C．not know | D．no known |
I am too glad _____ you.
| A．to see | B．seeing | C．saw | D．at seeing |
The Arctic is considered _____ the northern part of the Atlantic.
| A．having been | B．to have been | C．to be | D．being |
_____, the boy couldn't enter his house.
| A．Since the key had lost | B．The key being lost |
| C．Lost the key | D．Having lost the key |