Is _____ necessary to take off our shoes when we enter the computer lab?
| A．this | B．it | C．everyone | D．he |
We're still at the airport. If it weren’t for the delayed flight, we _____the concert right now.
| A．can be enjoying | B．must have enjoyed |
| C．would be enjoying | D．should have enjoyed |
It never occurred to humans until the mid-l990s some animals can be cloned.
| A．where | B．that | C．when | D．what |
—Will the match be cancelled because of the bad weather？
—No. Rain or shine，the match will be held as .
| A．schedule | B．scheduling | C．scheduled | D．to schedule |
Any help from you will be greatly appreciated. P1ease give me a reply at your earliest.
| A．interruption | B．instruction | C．consideration | D．convenience |
—That’s the third time he’s won the award in this field.
—Yes. He his maximum potential in the past decade.
| A．explored | B．is exploring | C．has been exploring | D．had explored |