While studying, fix your mind on what is really important, or you will __________ remembering nothing.
| A．take up | B．lead to |
| C．stick to | D．end up |
________ several times，he still couldn't understand how to operate the machine.
| A．Telling | B．Having told |
| C．To be told | D．Having been told |
Someone ________ his car in front of my house and it's blocking my way.
| A．was parking | B．parked |
| C．has parked | D．had parked |
________ here yesterday，he could have seen Jackie Chan.
| A．If Bob has come | B．If Bob came |
| C．If Bob had come | D．If Bob should come |
Some passersby witnessed the car accident ________ five passengers were killed，a baby included.
| A．in which | B．which |
| C．that | D．in that |
Never believe anything ________ other people have believed it.Use your own head.
| A．that | B．unless |
| C．because | D．once |