理论上讲下一步应该是发射能够观测化学信号的望远镜，以为生命的存在提供依据。有价值的信号包括氧气、水蒸汽和二氧化碳。
The next logical step would be a space telescope capable of picking up the chemical signatures of life, including the presence of oxygen, water vapour and carbon dioxide.
这无疑难以为该决定找到经济上的依据。
It is certainly difficult to find an economic rationale for the decision.
这些结论意味着总有一天医生们可以明确某种疾病是由病毒感染造成还是由细菌感染造成，这样就可以为医生是否处方抗生素提供明确依据。
Which means physicians could one day know whether to prescribe antibiotics, which can treat bacteria but not viruses.
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