In a new study of African elephants，researchers have four distinct characters that are among a group.
| A．convinced | B．identified | C．differed | D．existed |
–----Do you know our town?
------No, this is the first time I here.
A was
B. have been
C. came
D. am coming
I my washing machine the whole morning. I must get it done before noon.
| A．have repaired |
| B．am repairing |
| C．will repair |
| D．have been repairing |
-----Where _you_?
------I got caught in the traffic, or I would have been here earlier.
| A．did; go |
| B．had; gone |
| C．have; been |
| D．were; going |
A long time ago, I in the USA for two years.
| A．have lived |
| B．had lived |
| C．was living |
| D．lived |
So far the police no progress in the investigation of the case.
| A．has made |
| B．have made |
| C．has been made |
| D．had been made |