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．Mating habits of squid and octopus.B．The evolution of certain forms of sea life.C．The study of marine shells.D．Survival skills of sea creatures.
A．Mating habits of squid and octopus.
B．The evolution of certain forms of sea life.
C．The study of marine shells.
D．Survival skills of sea creatures.
单项选择题
A．To remind him of the data he should take to the conference.B．To see if be is ready for the coming conference.C．To tell him something about the conference.D．To help him prepare for the conference.
A．To remind him of the data he should take to the conference.
B．To see if be is ready for the coming conference.
C．To tell him something about the conference.
D．To help him prepare for the conference.
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