黑板擦干净了.The blackboard has been wiped clean.老师建议我们课后把黑板擦了.The teacher suggested that we ( should ) clean the blackboard after class.你可以用黑板擦把粉笔印擦掉.You can rub out the chalk marks with the eraser....
海水中盐的含量是多少?What is the concentration of salt in sea water?无机碱盐水溶液的饱和点通常随着温度和浓度的升高而降低,这将造成皂化剂中盐的析出,形成坚固的水垢.This causes the salt to drop out of solution, with net effect being a harden scale.本文简单地介绍了减少制革过程中盐污染的几种方法.Thus , ...