.
—Who______ it be that is knocking at the door?
—It ______ be Father, but I’m not sure.
| A．can; must | B．can; may | C．must; can | D．may; must |
-----Is this the first time youQuanzhou?
-----No. But the first time Ihere, the city wasn’t so beautiful.
| A．visited; came | B．visited; have come |
| C．have visited; have come | D．have visited; came |
After months of voyage, Columbus arrived in what laterto be a new continent.
| A．had been proved | B．was proved | C．had proved | D．proved |
we can’t remove our troubles in life forever, we can leave them behind when we are on vocation.
| A．When | B．While | C．Unless | D．Until |
Many migrant workers, city life, wouldn’t like to move back to the countryside.
| A．accustomed to | B．being accustomed to |
| C．have accustomed to | D．have been accustomed to |
The system has been designed to give students quick and easyto the digital resources of the library.
| A．way | B．approach | C．access | D．association |