Nobody noticed the thief slip into the house because the lights happened to__________.
| A．put up | B．give in | C．be turned on | D．go out |
Though the training cost a lot of time and effort, I do think it ______.
| A．valuable | B．significant | C．worthwhile | D．vital |
After careful consideration, he decided to take the position, ______ he knew it would be difficult for him.
| A．even though | B．now that | C．as if | D．so that |
The teacher handed our writings back to us, ______ some necessary changes.
| A．making | B．to have made | C．having made | D．made |
You must ______ that the power is off before you leave the lab.
| A．check | B．know | C．decide | D．examine |
At such gatherings, people ______ are not necessarily your relatives or friends.
| A．that you say hello | B．who say hello to |
| C．you say hello to | D．whom you say hello |