Only after David was asked to pay more attention ______ repeating the same mistake.
| A．he avoided | B．did he avoid |
| C．had he avoided | D．he had avoided |
_______ on the top of the mountain is an ancient tower ______ back to two hundred years ago.
| A．Standing；dating |
| B．To stand；to date |
| C．Having stood；dating |
| D．Stand；dated |
—Linda，the phone in your office can't be connected all the time.Why?
—Oh，sorry，Miss Miles.The service________since last Wednesday.
| A．has been stopped |
| B．has stopped |
| C．was stopped |
| D．had stopped |
—Good morning，Doctor White's office.
—Hello，this is John Woods.Could you please tell Doctor White I________？My car won't start.
| A．was delayed |
| B．will be delayed |
| C．am delaying |
| D．would delay |
It's only six o'clock now；little Tom should be up，though，because he________for nine hours.
| A．has been sleeping |
| B．had been sleeping |
| C．has slept |
| D．had slept |
—Have you met Mr.Li?
—Yes.When I arrived，he________for Shanghai to attend a national conference.
| A．just left |
| B．had just left |
| C．just leaves |
| D．was just leaving |