If we don't put the meat in the fridge, it may ().

单项选择题Only one horse can go through the door ().

A．at once time
B．at a time
C．in once time
D．in no time

单项选择题Great changes () in our country since twenty years ago.

A．have taken place
B．have been taken place
C．took place
D．have been happened

单项选择题Tom's parents will be back from London ().

A．long before
B．before long
C．before soon
D．soon after

单项选择题The car runs () 80 kilometres an hour,

A．at
B．in
C．with
D．on

单项选择题The teacher can () believe that Tom studies so ().

A．hardly; hardly
B．hard; hardly
C．hardly; hard
D．hard; hard

单项选择题Some good advice () the students by the teachers in this school.

A．were given
B．were given to
C．was given
D．was given to

单项选择题The teacher () the map on the blackboard.

A．hang
B．to bang
C．hung
D．hanged

单项选择题They will do () they can to overcome () great difficulties there may be.

A．that; whatever
B．what; whatever
C．what; which
D．which; what

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