according to need (physicians use PRN in writing prescriptions);
"add water as needed"
双语例句
1. PRN combined feature selection algorithm is proposed.
并提出改进的PRN组合特征选择算法。
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2. Methods: We observe the effect of using Intravenous Catheter System with PRN 139 cases and analyse the factors which influence it.
方法：观察139例浅静脉留置针临床使用效果，分析其影响因素。
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3. The former is used to achieve the fine estimation of the carrier frequency while the later is used to achieve the fine estimation of the code delay of the PRN code.
载波跟踪环用于对接收信号的载波频率进行精确跟踪，而码跟踪环是用于实现伪随机码延时的精确对准。
youdao
4. The former is used to achieve the fine estimation of the carrier frequency while the later is used to achieve the fine estimation of the code delay of the PRN code.
