We _________ our breakfast when an old man came to the door.
| A．just have had | B．have just had |
| C．just had | D．had just had |
The committee __________ over the problem among themselves for two hours.
| A．has argued | B．has been arguing |
| C．have argued | D．have been arguing |
—Liu Fang, I don't know you can play the Pipa and Guzheng so well.
—Well, actually I __________ it since I was six years old.
| A．plays | B．have been playing |
| C．played | D．had been playing |
Betty and Louis __________ with each other at first sight and they __________ in love for five years ever since.
| A．fell in love; have been | B．fell in love; have fallen |
| C．were in love; have been | D．were in love; have fallen |
I like these English songs and they __________ many times on the radio.
| A．taught | B．have taught |
| C．are taught | D．have been taught |
By the time he realizes he __________ into a trap, it'll be too late for him to do anything about it.
| A．walks | B．walked |
| C．has walked | D．had walked |