English is useful subject.
| A．a | B．an | C．the | D．/ |
John didn’t go to bed ______he finished his homework.
A.until B.after C.while
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