Don’t answer the phone when the cell phone is being charged, for it ________ be very dangerous sometimes.
| A．shall | B．should |
| C．can | D．must |
The president spoke at the business meeting for nearly an hour without ______ his notes.
| A．bringing up | B．referring to |
| C．looking for | D．trying on |
The printer has left two lines from this paragraph.
| A．off | B．out | C．over | D．with |
The officer demanded that such things ______from happening again.
| A．prevented | B．prevent | C．be prevented | D．were prevented |
The secretary worked late into the night,_______ a long, speech for the president.
| A． to prepare | B．was preparing | C． prepared | D．preparing |
Please remain _______; the winner of the prize will be announced soon.
| A．seating | B．seated | C．to seat | D．to be seated |