点火负压是指点火器下部()的负压,即真空度。
参考答案:风箱
When speaking in public, it is important to _____ your message _____ and keep the attention of your audience. [ ]
A. get…through
B. get…into
C. get…over
D. get…across
压传动能方便地实现:()。
A、无级调速
B、调速范围大
C、调速功能受功率大小限制。