－When do we need to pay the balance?
－__________ September 30.
| A．In | B．By | C．During | D．Within |
— Did Jack come back early last night?
— Yes. It was not yet eight o’clock ______ he arrived home.
| A．when | B．before | C．that | D．Until |
Not until she took off her glasses ______ she used to be my neighbor.
| A．I realized | B．I had realized |
| C．had I realized | D．did I realize |
The new teaching building ______ by the end of last month.
| A．has been designed | B．had been designed |
| C．was designed | D．would be designed |
Was it because Jack come late for school ______ Mr Smith got angry?
| A．why | B．who | C．where | D．that |
Most American children go to state schools, but the private schools ______ be very good.
| A．must | B．can | C．should | D．may |