My Daytime is Your Nighttime

In today's leeson,we are going to talk about two things.

• Why do we have time zones
• How to deal with time differences across time zones

Part 1:Why do we have time zones

Because of the Earth's rotation,the Earth is divided into time zones.
It takes 24 hours for the Earth to make a complete rotation.
There are 24 time zones on the Earth.

standard time zone 标准时区
geographical time zone 地理时区
Many accidents happened because train conductors used different clocks.
The endless schedules on the train tickets confused many people.
Some countries,sucn as the US,have several time zones.
One large country,China,has just one time zone for the whole country.

There are 4 standard time zones in US
Pacific Standard Time 西部标准时间    eg: Los Angels
Mountain Standard Time 山区标准时间   eg: 菲尼克斯
Central Standard Time 中部标准时间    eg: Chicago
Eastern Standard Time 东部标准时间    eg: New York

There is only one standard time zone
Bejing Standard Time 北京时间 （中国的标准时）
Greenwich Mean Time 格林尼治时间（英国的标准时）

Every year some countries move their clocks forward in the spring - 
and move them back in the autumn.
Daylight Saving Time 日光节约时/夏令时

Part 2:How to deal with time differences across time zone

When it's daytime in the US,it's nighttime in China.
When it's daytime in one place,it's nighttime in another place.
When it's 10 a.m in New York,it's 7 am in San Francisco.

There's a time difference between A and B. 
In fact,there's a 12-hour time difference between Boston and Shanghai

There's no time difference between A and B.
There is no time difference between China and Singapore.

A is ahead of B 
B is behind A
Shanghai is 12 hours ahead of Boston in summer.
Boston is 12 hours behind Shanghai in summer.

How to deal with time difference
1.you have to be patient
2.take advantage of the World Clock on your smartphone.
3.schedule calls in advance

telephone conference 电话会议
video conference 视频会议

How to arrange a conference that crosses time zones ? 
1.We can use a shared calendar to find an open slot on everyone's schedule.
2.Send emails to confirm with all attendees.
3.You should send reminders to all attendees before the meeting.

For travelers,this means it can be very difficult to sleep after a long flight. 
The clock may say 8:00 pm,but for your body it's noon.
Travlers across several time zones causes jet lag.
This is called jet lag. 

suffer from jet lag 遭受时差反应的折磨
I'm still suffering from jet lag after my trip to Boston

How to  beat jet lag when we travel across time zones?
1.Get  a good night's sleep before you fly
2.During the trip,drink a lot of water and avoid coffee or wine.
3.You can take a small dose of melation