_____ mobile phone is very convenient, school children are not allowed to own one.
| A．If | B．While | C．Because | D．When |
—Is everyone here? —Not yet ... Look, there _____ the rest of our guests!
| A．come | B．comes | C．is coming | D．are coming |
Listening to loud music at rock concerts _____ caused hearing loss in some teenagers.
| A．is | B．are | C．has | D．have |
Such poets as Shakespeare _____ widely read, of whose works, however, some _____ difficult to understand.
| A．are; are | B．is; is | C．are; is | D．is; are |
The factory used 65 percent of the raw materials, the rest of which _____ saved for other purposes.
| A．is | B．are | C．was | D．were |
One third of the country _____ covered with trees and the majority of the citizens _____ black people.
| A．is; are | B．is; is | C．are; are | D．are; is |