With train tickets not easily and flights too expensive, bicycles become a popular method of transportation for many budget travelers.
| A．accessible | B．available |
| C．admissible | D．adaptable |
.In that country, the rich ______ richer, the poor, poorer.
| A．become | B． has become | C．becomes | D．is becoming |
.The project requires more labor than ______ because it is extremely difficult.
.Not one in one hundred children exposed to the disease ______ likely to develop it.
| A．should be | B．must be | C．is | D．are |
Robert is said ______ abroad，but l don't know what country he studied in．
| A．to have studied | B．to study | C． to be studying | D．to have been studying |
The purpose of new technologies is to make life easier，______it more difficult．
| A．not make | B．not to make | C． not making | D．don't make |