内容正文：
Unit 3 Back to the past
Welcome to the unit
Looking into a mirror, we can see true images of our own; with our knowledge of the past, the present can be better known.
—Chen Shou
What does the quotation from Chen Shou mean?
Since the past is so important, can we humans go back to the past?
How?
a machine that enables you to travel in time to the past or the future
时间机器（能使人往返于过去或未来）
By daydreaming.
By watching TV.
By reading books.
By traveling through the time machine.
Watch a video—The Time Machine
Read the excerpt (摘录) on P29 about the time machine and finish the following reading card.
The name of the book
The author
The main character
The main character’s view
The way to support his view
The plot to be continued
The Time Machine
H. G. Wells
The time traveller
There is a fourth dimension——Time.
He conducted an experiment with a model of the Time Machine.
He moved in Time and got enough proof to convince the group.
Length
Breadth
Thickness
Discussion
If you had a time machine, which dynastic would you go back to?
Which historical figure would you like to meet?
What would you like to say to him/her?
If you had a time machine, which dynastic would you go back to?
Which historical figure would you like to meet? Why?
What would you like to say to him/her?
If I had a time machine, I would like to go back to the Tang Dynasty. I have always been fascinated by Chang’an, so I wish I could travel to the ancient capital and see what life was like back then.
I would like to meet Li Bai or Du Fu. I love their poetry, so it would be really amazing to meet them. I would ask them many questions about their poems and why they wrote them. For example, “Mr Li Bai, why do you include the image of the moon in your poems so often? Does the moon have special meaning to you?” “Mr Du Fu, why do your poems show great concern for the country and common people?”
If I had a time machine, I woul