开式齿轮传动的主要失效形式是(),闭式软齿面齿轮传动的主要失效形式是(),闭式硬齿面齿轮传动的主要失效形式是()。
参考答案:磨粒磨损;齿面塑性变形;齿面点蚀;
A joint probability of A and B must always be:()
A. less than or equal to the conditional probability of A given B.
B. greater than or equal to the conditional probability of A given B.
C. greater than or equal to than the probability of A or B.
如何确保教育实践活动扎实有效推进?