In history, the Romany split into different groups and developed their own language, _______ there are now approximately sixty varieties.
| A．by which | B．of which | C．by whom | D．of whom |
The Jews _____ a series of disasters in World War II, because the German Nazis wanted to kill all of them.
| A．went over | B．went after | C．went for | D．went through |
The NBA is _____ organization of professional（职业的） basketball players in the USA.
A. a B. an C. the D. /
We used to work in the same office and we _________ have coffee together.
| A．would | B．should | C．could | D．might |
_____ all the inventions have in common is ______ they have succeeded.
| A．What; what | B．That; what | C．What; that | D．That; that |
The new machine，if _________ properly，will work at least ten years.
| A．use | B．using | C．being used | D．used |