Unit 4 Breaking boundaries Using language 课件-2022-2023学年高中英语外研版（2019）选择性必修第二册

新外研社高中英语选择性必修二Unit 4 Breaking boundaries Using Language Grammar 2 Underline the sentences below in the reading passage. But it is vital not to take any chances. ...it was my duty as a doctor to go there and offer my help. It is important to remember that Ebola doesn't respect national boundaries. It is so inspiring to have colleagues like Wilton, Maisy and Alfono, not mention all... ... it is absolutely essential for us all to collaborate to create a global community... What does “it” refer to in sentences (a) and (c)? a But it is vital not to take any chances. b But not to take any chances is vital. c It is important to remember that Ebola doesn't respect national boundaries. d To remember that Ebola doesn't respect national boundaries is important. “It” refers to “not to take any chances” in sentence (a) and “to remember that Ebola doesn't respect national boundaries” in sentences (c). a But it is vital not to take any chances. b But not to take any chances is vital. c It is important to remember that Ebola doesn't respect national boundaries. d To remember that Ebola doesn't respect national boundaries is important. 2 What is the difference between the sentences in each group? Why does the author choose to use sentences (a) and (c) instead of (b) and (d)? The first sentences in each group use “it” as an empty subject at the beginning of the sentences. The reason why sentences (a) and (c) are chosen is that the sentences are kept balanced and the key information of the sentences is emphasised. summary It as an empty subject it作形式主语 It作为形式主语，所代替的是句子的逻辑主语，并无实际词义。这可以保持句子的结构平衡，避免主语太长，显得头重脚轻。 1 （1）不定式。句子的谓语可以是： ① be+形容词； e.g. It is important ________ (know) your limitations. 知道自己的局限性是很重要的。 ② be+名词； e.g. It is a good idea _____ _(have) a little notebook handy. 手边有个小笔记本是个好主意。 It做形式主语的基本用法： to know to have 1 （1）不定式。句子的谓语可以是： ③ be+介词短语； e.g. It is against