单项选择题

There is supposed to be a safety ________ which makes it impossible for trains to collide.

A．appliance
B．accessory
C．machine
D．mechanism
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单项选择题
Throughout the year of 1939, there was a ________ rising rate of inflation in the United States. It reached to 10%.
A．firmly
B．sharply
C．constantly
D．roughly
单项选择题
We must look beyond ________ and assumptions and try to discover what is missing.
A．justifications
B．illusions
C．manifestations
D．specifications
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