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 |
It has been announced that candidates(应考者) ________ remain in their seats until all the papers have been collected.
| A．can | B．will |
| C．may | D．shall |
I ________ pay Tracy a visit, but I am not sure whether I will have time this Sunday.
| A．should | B．might |
| C．would | D．could |
The book was written in 1946, __________ the education system has witnessed great charges.
| A．when | B．during which | C．since then | D．since when |
—Where did you get to know her?—It was on the farm __________ we worked.
| A．that | B．there | C．which | D．where |
Some pre-school children go to a day-care center, __________ they learn simple games and songs.
| A．then | B．there | C．while | D．where |