After the new machine was introduced, the factory produced _____ in 2011 as the year before.
| A．twice as many machines |
| B．twice many as machines |
| C．as twice many machines |
| D．as many machines twice |
the difference between the two research findings will be one of the worst mistakes you make.
| A． | Ignore | B． | Ignoring |
| C． | Ignored | D． | Having ignored |
I'm soto all those volunteers because they helped my terrible day end happily.
| A． | special | B． | superior | C． | grateful | D． | attractive |
A ship in harbor is safe, but that’s not ______ ships are built for.
| A．what | B．whom | C．why | D．when |
Just as I got to the school gate, I realised I ______ my bank in the cafe.
| A．have left | B．had left |
| C．would leave | D．was leaving |
scientists have learned a lot about the universe, there is much we still don't know.
| A． | Once | B． | Since | C． | Though | D． | Unless |