.It’s about a time _____ there were black slaves in North America.
| A．where | B．when | C．how | D．that |
—What happened?
—Well, the wind _____ the door open. I' ve already closed it.
| A．is blowing | B．has blown | C．blew | D．had blown |
I became a teacher in 1993. I _______ for 13 years by next summer.
| A．has taught | B．will teach | C．has been teaching | D．will have been teaching |
.—Have you finished your composition already, Jack?
—Yes, I ____ it within half an hour.
| A．have finished | B．finished | C．finish | D．had finished |
No conclusion _______ about whether to tear down the old buildings for a theme park until several discussions have been made．
| A．will be reached | B．is reached | C．is being reached | D．had been reached |
In recent years many football clubs ______ as business to make a profit.
| A．have run | B．have been run | C．had been run | D．will run |