F．作状语的动词-ing形式

  1．动词的-ing形式作状语时，其逻辑主语一般应与句子的主语保持一致。
  Entering the classroom, I found nobody in it.走进教室，我发现里面没人。（entering的逻辑主语是I，相当于when I entered the classroom, I found nobody in it.）
  如-ing形式表示的动作不是句中主语发出或承受的，那就是误用。这种无依着的-ing形式，语法上称之为“垂悬分词”。
  【误】Looking out through the window, the garden was beautiful.（looking out through the window的逻辑主语是the garden，显然不对）
  【正】Looking out through the window, we saw a beautiful garden.从窗户看出去，我们看见一个漂亮的花园。
  【误】Reading the evening newspaper, a dog started barking.（逻辑主语是dog，它不会看晚报）
  【正】I was reading the evening newspaper when a dog started barking.我看着晚报的时候，一只狗开始叫起来。
  2．如不能和句子中的主语保持一致，该-ing形式必须有自己的逻辑主语，通常有名词或代词来担任。
  The last bus having gone, we had to walk home.末班车已经开走了，我们不得不走回家。（having gone的逻辑主语是the last bus，而不是we）
  Time permitting, the football match will be played on Friday.天气允许的话，足球赛将在周五举行。（permitting的逻辑主语是time，而不是the football match）
  注意：
  高中阶段有一些固定的-ing形式短语，如generally speaking, judging from..., considering..., talking of..., supposing...等，它们的逻辑主语可以和句子的主语不一致。这种-ing短语可当作一个插入语。
  Generally speaking, boys are more interested in science than girls.      一般说来，男孩比女孩对科学更感兴趣。
  Judging from his accent, he must come from Canada.从他的口音看，他一定来自加拿大。
  Considering how poor he was, we decided to let him attend the concert for free.考虑到他是多么的穷，我们决定让他免费听音乐会。
  Supposing it rains what will you do假使下雨，你会怎么办呢？