A good idea _________ to him, and he knew _______ to do next.
| A．happened , what | B．appeared ,how | C．occurred ,what | D．arrived ,how |
______ I'm willing to help, I do not have much time available．
| A．While | B．When | C．Once | D．Since |
The rise of oil prices made scientists search for new energy resources ______ oil．
| A．replace | B．replacing | C．to replace | D．replaced |
You didn't believe John won the first prize at the speech competition, ______?
| A．did he | B．didn't he | C．did you | D．didn't you |
I had reached a point in my career _____ I needed to decide which way to go．
| A．why | B．which | C．when | D．where |
Here are some new computer programs _____ for home buildings．
| A．designing | B．design | C．to design | D．designed |