______ do we owe the discovery of the wild land?
| A．What | B．Who |
| C．To whom | D．For what |
To my surprise, he turned up in the room without ___.
| A．noticed | B．being noticed | C．noticing | D．to be noticed |
He is a ___ friend of mine.
| A．close | B．silent | C．quiet | D．near |
--Do you know which path __ the park? ---The one on your right.
| A．to lead | B．leading to | C．leads to | D．led to |
I always do all the cleaning __ on Sunday.
| A．self | B．alone | C．lonely | D．lone |
They all appeared ___ this song before.
| A．to learn | B．to have learned | C．to not have learned | D．not learning from |