独立语 the detached phrase
   The detached phrase is structurally not related to any other part of the sentence in which it appears. It is often used to express a subjective point of view or attitude, to make a attitude, to make a speculation, assessment, explanation, or illustration, or to call attention to something. The expression “总的来说”, “大家都知道” , and “ 重要的是” in this lesson, as well as “ 我看”, and “比如说” from the previous lesson, are all examples of detached phrases. They may be placed at the beginning or in the middle of a sentence, for example,
  
  大家都知道，中国的封建社会有两千多年的历史。
  总的来说，家务事儿妇女要比男人干得多了。
  中国的经济虽然发展得很快，但总的来说，中国还是发展中国家。 
  重要的是，男女都应该有公平竞争的机会。
  一般地说，妇女只有社会地位提高了，在家庭里的地位才能提高。