What were you doing ______ I knocked at the door?
I was sleeping.( )
A.unlessB.onceC.whenD.while
This math problem isn't so difficult that I can work it out ________.( )
A.easilyB.usefullyC.loudlyD.quietly
Don't ________ the chance when you can catch it,or you will regret.( )
A.guessB.missC.rememberD.allow
Are you clear about the job of a policeman,Ben?
Yes,to keep people ________ and the society in good order.( )
A.busyB.safeC.luckyD.healthy
The earlier kids learn to be independent,the ________ it is for their future.( )
A.goodB.wellC.betterD.best
It's a good habit to wash your hands ________ you have meals.( )
A.unlessB.whileC.whenD.before