【单选题】由于长时间工作使元件产生疲劳引起的损坏是 。 A 气蚀失效 B 污染失效C 泄露失效 D 疲劳、老化与断裂失效
【单选题】There must be ______ book which could help .
【简答题】基因频率(gene frequency)
【判断题】水深小于5m的河流,可在采样垂线中点处设置一个采样点。
【判断题】FREQUENCY为计算频率的函数。()
【简答题】基因型频率(genotypic frequency)
【单选题】The frequency 频率 of an alternator is controlled from the main switchboard by adjusting the_____.