Dickson left his father’s firm and ____business on his own.
| A．started out | B．launched into | C．began on | D．worked at |
David helps his mother with her housework every Saturday for about _____.
| A．one and half hours | B．a half and an hour |
| C．an hour and half | D．one and a half hours |
Professor Smith, along with his assistants, _____ on the project day and night to meet the deadline.
| A．work | B．working | C．is working | D．are working |
20．Tell John not to leave the house unless he_____________that the lights .
| A．will make sure，turn off | B．makes sure，are turned off |
| C．will make sure，will turn off | D．makes sure，will be turned off |
19．Mrs．Brown is so_________about her housework that few servants Want to work for her．
| A．skillful | B．neat | C．particular | D．Special |
18．After you have used the dictionary，please just put it back_________it belongs．
| A．to whom | B．to which | C．what | D．Where |