51、 Paper making in China _________from there to North Africa and Europe.
A．sprang
B．spilled
C．carried
D．spread


52、 Everything we eat and drink contains some salt; we can meet the body' s need for it from natu-ral sources without turning_________the salt bottle.
A．up
B．to
C．on
D．over


53、 If you want to become a doctor, you ought to study _________
A．medicine
B．the medicine
C．literature
D．the literature


54、 During the voyage, Darwin collected a good deal of information about living things, which_________led to his famous book "On the Origin of Species".
A．lastly
B．completely
C．essentially
D．eventually


55、 You should have been more patient_________ that customer; I' m sure that selling him the watch was a possibility.
A．of
B．with
C．for
D．at


56、 A country must always be_________guard against spies and invaders.
A．in
B．to
C．with
D．on


57、 He had been to ________give up much of his time to housework.
A．ordered
B．persuaded
C．compelled
D．frightened


58、 My brother is now working______ he did last year.
A．much harder than
B．more harder than
C．more than
D．much than

59、 Sometimes children have trouble_________ fact from fiction and may believe that such things
actually exist.
A．to separate
B．separating
C．for separating
D．of separating


60、 The chances of discovering life on Neptune are about a million_________
A．at one
B．for one
C．to one
D．against one