You could construct a loop here but that feels at odds with R 's functional and vector-oriented operations . Instead the trick is to use the function apply ()

可能会在这里构造一个循环，但是这与R的功能和 面向 向量的操作不 一致。

Positive-strand RNA virus reverse genetics system is an useful tool in viral replication pathogenesis research screening antiviral drugs and new vaccines vector-oriented areas such as the preparation .

而正链RNA病毒的反向遗传操作系统在病毒复制、致病机制研究，抗病毒药物筛选和新型疫苗、 导向 载体制备等方面是一个 极其有用的工具。