---Will you come over to Beijing for the May Day holiday?
---I’d like to, but my family the 2010 World Expo in Shanghai during the holiday.
| A．are visiting | B．are to visit | C．will be visiting | D．will visit |
The field research will take Joan and Paul about five months; it will be a long time __________ we meet them again.
| A．after | B．before | C．since | D．when |
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 |