单项选择题

A．If they don’t involve any risks.
B．If they produce predictable side effects.
C．When the urgent need for them arises.
D．When tests show that they are relatively safe.
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单项选择题
A．The long wait.B．The broken-down computer.C．The mistakes in her telephone bill.D．The bad telephone service.
A．The long wait.
B．The broken-down computer.
C．The mistakes in her telephone bill.
D．The bad telephone service.
单项选择题
A．To chat with Jack socially.B．To get help in the course.C．To hand in their assignments.D．To practice giving interviews.
A．To chat with Jack socially.
B．To get help in the course.
C．To hand in their assignments.
D．To practice giving interviews.
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