E-mail, as well as telephones, ______ an important part in daily communication.
| A．is playing | B．have played | C．are playing | D．play |
raining hard for 3 hours without stopping.
| A．It is | B．It was | C．It has been | D．It had been |
—My home is in that tall building over there.
— ?
| A．Can it see | B．Can see it | C．Can be seen it | D．Can it be seen |
.—It is raining cats and dogs.
— ..
| A．So it is | B．So is it | C．Neither it is | D．Neither is it |
Someone is at the door, who is ?
| A．this | B．that | C．it | D．he |
.In the United States, bus travel doesn't cost much as train travel, ?
| A．don't they | B．does it | C．do they | D．doesn't it |