—At present, one of the best ways to study is working in groups.
—More chances ___________ to students to learn from each other.
| A．offer | B．are offered |
| C．have offered | D．are offering |
It took him half an hour _____ the work.
A.doingB.to do C.did
The teachers are very friendly ______their students.
A.to B.at C.on
His shoes are ___dirty ____he has to wash them .
A.too, to B.so, that C.enough, that
She missed the bus,_____she had to walk home.
A.so B.but C.because
The Greens will have ______holiday in China.
A.two weeks B.two-week C.a two-week