非谓语动词与独立主格：短语，句子(或者句子，短语)
1.当短语部分有独立主语，并且该主语不同于句子主语，这时短语结构称为独立主格。(它最明显的特点是短语部分有独立的主语)。
独立主格的结构1：名词(代词)+ 分词 [现在分词、过去分词]
现在分词表示主动的，正在进行的行为;过去分词表示被动的，已经完成的行为。 作题时要通过判断动作与名词(代词)之间的关系来确定是使用现在分词还是过去分词。当动作由名词(代词)发出时使用现在分词，而名词(代词)是受动者时则用过去分词。
54. Silver is the best conductor of electricity， copper _B_ it closely.
A followed B following C to follow D being followed
49. All things _A_， the planned trip will have to be called off.
A considered B be considered C considering D having considered
call off 取消; cancel vt. 取消; 四级中的考点就是现在分词和过去分词的区别。
独立主格的结构2：with + 名词(代词)+ 分词 [句子当中作状语]
36. After the Arab states won independence， great emphasis was laid on expanding education， with girls as well as boys _C_ to go to school.
A to be encouraged B been encouraged C being encouraged D be encouraged
as well as 和(相当于and); be encouraged不会考。
动词不定式有预示将来行为的含义。to be encouraged 将要被鼓励;
been encouraged 已经被鼓励完了，与主句的谓语动词相对;being encouraged 正在被鼓励
