If we________a table earlier，we couldn’t be standing here in a queue.
| A．have booked | B．booked |
| C．book | D．had booked |
Hardly____into the country____it began to rain.
| A．we had got;when | B．we got;than |
| C．had we got;when | D．did we get;than |
It is I____singing in the garden.
| A．who are | B．who is | C．that am | D．that is |
It was____the old worker came that we____the experiment.
| A．until;didn’t begin | B．not until;began |
| C．until;began | D．not until;didn’tbegin |
____be careful when crossing the street!
| A．Must | B．Should | C．Ought to | D．Do |
___come again.
| A．Do | B．Can | C．May | D．Did |