【判断题】2-72 只要力系的合力等于零,该力系就是平衡力系,
【简答题】It can fly in the sky and bring people.
【单选题】The sky-scrapers stand out ______ the blue sky.
【简答题】阅读理解。 What is the sky? Where is it? How high is it? What lies above the sky? I am sure you have often asked these questions. They are very difficult to answer, aren't they? If someone asks you:'What c...
【判断题】对铁的表面进行电镀,可以减缓铁的生锈速度。