【单选题】若对心尖顶直动从动件盘形凸轮机构的推程压力角超过了许用值,在不改变从动件运动规律的情况下,可采用____措施进行改进。
【多选题】对心尖顶直动从动件盘形凸轮机构改为左偏置后,若凸轮逆时针转动,以下描述正确的是( )。
【多选题】Natural materials include ().
【单选题】The MIT team had tried different materials before they studied natural silk in their research. 查看材料
【多选题】对心尖顶直动从动件盘形凸轮机构改为适当右偏置后,若凸轮逆时针转动,以下描述正确的是( )。
A.
会减小推程段压力角,但同时增加回程段压力角;
【单选题】It can be inferred from the passage that________
A.
natural materials are safe in food processing
B.
chemicals are needed in food processing
C.
food poisoning can be kept under control
D.
food poisoning is out of control
【多选题】若对心尖顶直动从动件盘形凸轮机构的推程压力角超过许用值时,可采用 ____ 措施来解决。