It 句型

1. Basic structure:
There + be + subject + adverbial

2. Non-finite structure
There to be --------- for ; Verb
There being ---------in,on….; noun; adverbial
There being a lawn extends from the river to the house.
There is a lawn extending from the river to the house.
There extends a lawn from the house to the river.
From the house to the river lies a lawn.
From the wall comes the voice of the doctor.

It:

1. Reference it:
Beijing is a big city. It is the capital of China.

2. Non-reference it
A. Empty it
B. Anticipatory it
C. Cleft it

It 句型包括由“非指代性it”作型式主語的三種句子：第一種是以it作形式主語的表示時間、距離、天氣等意義的句子；第二種是以it作先行主語的句子；第三種是以it作引導詞的分裂句。

Empty it
虛義it是一種非指代性it，以區別于人稱代詞it，常用作沒有具體意義的主語，出現于表示氣候、天氣、溫度、時間、地點、距離等意義的句子中。也用來表示一般的籠統的情況。也用于一些結構及習慣語中。

Eg.
It’s fine today, isn’t it.
It was dull when Mary was away.
It looks as if the college is very small.
Hop it. (Go away)