润滑油是如何进行润滑作用的?
参考答案:润滑油在作相对运动的两摩擦表面之间形成油膜,以减低磨损,降低摩擦功耗,洗去磨损形成的金属微粒,带走摩擦热,冷却摩擦表面。
根据母或汉语提示填空。
1. We should be _____ (镇静的, 沉着的) before danger.
2. The l_____ snow can make the wheat warm.
3. Dennis i _____ the warning and put his hand into the lion's cage.
4. He was caught c _____ in an exam.
5. Because he didn't finish the work on time and was fined by the
company, he was very u_____ about it.
简述成本计划评审法的基本要点。