齿轮传动设计时，软齿面闭式传动通常先按（）设计公式确定传动尺寸，然后验算轮齿弯曲强度
参考答案：齿面接触强度
He was proud of being chosen to participate in the game and he ______ us that he would try as hard as possible.
a. insured b. ensured c. assumed d. assured
幼龄期体壁较薄，药剂防治效果较好。
