41、Vitamins are complex ________ that the body requires in very small mounts.
A．matters
B．materials
C．particles
D．substances
42、Apart from caring for her children, she has to take on such heavy ________ housework as carrying water and firewood.
A．time-consumed
B．timely-consumed
C．time-consuming
D．timely-consuming
43、Anna was reading a piece of science fiction, completely ________ to the outside world.
A．having been lost
B．to be lost
C．losing
D．lost
44、The police are trying to find out the ________ of the woman killed in the traffic accident.
A．evidence
B．recognition
C．status
D．identity
45、All human beings have a comfortable zone regulating the ________ they keep from someone they talk with.
A．distance
B．scope
C．range
D．boundary
46、We have planned an exciting publicity ________ with our advertisers.
A．struggle
B．campaign
C．battle
D．conflict
47、________ the help of their group, we would not have succeeded in the investigation.
A．Besides
B．Regardless of
C．But for
D．Despite
48、________ much is known about what occurs during sleep, the precise function of sleep and its different stages remains largely in the realm of assumption.
A．Because
B．For
C．Since
D．While
49、John doesn’t believe in ________ medicine; he has some remedies of his own.
A．standard
B．regular
C．routine
D．conventional
50、Owing to ________ competition among the airlines, travel expenses have been reduced considerably.
A．fierce
B．strained
C．eager
D．critical