虽然它们听起来很高效而且节约成本，但最近的一项研究表明，它们并不有效，主要是因为抑郁症患者与之接触的可能性低，也难以坚持下去。

While they sound efficient and cost-saving, a recent study reports that they are not effective, primarily because depressed patients are not likely to engage with them or stick with them.

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Now, the other nice thing about viruses is not only are they very efficient but most viruses are specific for certain kinds of cells.

病毒的另一个绝妙之处在于,它们不仅高效,对特定细胞的特异性也很好

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