1、本网站免费注册后即可以下载，点击开通VIP会员可无限免费下载！
2、资料一般为word或PPT文档。建议使用IE9以上浏览器或360、谷歌、火狐浏览器浏览本站。
3、有任何下载问题，请联系微信客服。
扫描下方二维码，添加微信客服
选修9《Warming up、Pre-reading、Reading、Comprehending》精品PPT课件优质课下载
2 Who was the first person that discovered the “New World”?
Columbus
early navigational instrument
compass
sextant
sea chart
astrolabe
Using celestial bodies
Picture 1 to plot the positions
Picture 2 to work out the latitude
Picture 3 a special cloud formation indicates there is land close by
Using wildlife
Picture 1 If seaweed was fresh and smelled strongly, the ship was close to land.
Picture 2 Sea birds could be used to show the way to land when it was nowhere to be seen.
Using the weather
Picture 1 to help identify the position of a stream or river when…
Picture 2 to direct their sailing
Use the information to analyze the navigational skills and write the answers in your own words.
1.To find the ship’s position at sea a sailor used
the North Star and the sun.
2.A sailor knew that land was nearby if he saw
clouds, fresh seaweed ,nesting birds or fog.
3.Sailors used
to accelerate their speed.
sea currents or tides and winds