They will do () they can to overcome () great difficulties there may be.

单项选择题This device will help the () detectives see things that may remain ().

A．advanced; hidden
B．advancing; hiding
C．advanced; hiding
D．advancing; hidden

单项选择题The president's visit to Japan had a positive effect () business () science and technology between the two countries.

A．on; as well as
B．to; as well
C．about; as well
D．in; as well as

单项选择题The workers are making radios, TV sets and some () things in this factory.

A．another
B．others
C．the others
D．other

单项选择题The headmaster went to Washington () the first time last September.

A．for
B．on
C．at
D．in

单项选择题About 70 percent of the population()in that country in the mountains and only 30 percent of its land () farmland.

A．lives; are
B．live; are
C．live; is
D．lives; is