For our middle school students, some courses are compulsory, while others are ________.
| A．flexible | B．optional | C．impressive | D．significant |
Among the 15-year-old children, some studying in university while others are still learning to read and write.
| A．should have been | B．would have been | C．can be | D．must be |
Personally I think it is the sales manager, rather than the sales girls, ______ to blame.
| A．is | B．that is | C．are | D．who are |
Albert Einstein, life had once been very hard, was given the Nobel Prize for physics in 1921
| A．of whom | B．for whom | C．for whose | D．in whom |
Mr. White his racing bicycle by himself yesterday, but I am not sure whether it is ready.
| A．repaired | B．had repaired | C．was repairing | D．would repair |
English for more than six years, he can speak and work very well with that businessman from England.
| A．To have learned | B．To learn | C．Learning | D．Having learned |