【文章內(nèi)容簡介】 ur notebook all the useful expressions and make sentences of your own with them. sail the oceans, explore the oceans, plot a ship39。s position on a map, the voyages of travelers, before the 17th century, at the mercy of?, have modern navigational aids, read these pages from an encyclopedia use nature to help, keep alongside the coastline, seem to have been?, the first and most useful form of exploration, carry the minimum amount of risk use celestial bodies, North Star, at the North Pole, at its highest position in the sky, at the equator, along the horizon, acplished navigators, be able to use?to plot their positions, on a clear day, during the summer, use the sun overhead at midday to navigate by, use the height of the sun to work out their latitude, observe the clouds over islands, a special cloud formation, land close by use wildlife, see seaweed in the sea, tell?by the colour and smell, flesh and smelled strongly， close to land, use sea birds to show the way to land, in the evening, nesting birds, return to land and their nests, follow the birds to land, in the open sea use weather, gather at sea, as well as over streams or rivers, identify the position of a stream or river, close to land, use the winds to direct one’s sailing, accelerate the speed, observe the winds, before and during one’s outward or return journeys． use the sea, carry ships to their destination, explore the seas, discover new lands, increase their ability to navigate new seas, use instruments use navigational instruments to help?, find longitude, secure method of measuring longitude, solve this theoretical problem, move westwards, 15 degrees every hour, method of calculating longitude, use speed and time, method of measuring speed, tie to?, over the side of the ship, throw?into?, advance through the water, pass through?, during a fixed period of time, give the speed of?, in nautical miles per hour, use the pass, use plicated mathematical tables, have a special magic pointer, indicate the North Pole, find the direction, in this way, set a straight course, in the middle of the ocean． find latitude, the Bearing Circle, measure the sun39。s position, measure the sun’s shadow, pare?with?, the height of the sun at midday, sail on?, rather than a random course a special allinone tool for telling the position of the ship, in relation to?, give sb the local time, find one’s latitude at sea, use as one of the points of reference, a more precise and simplified version of the astrolabe, above the horizon, use a quarter circle, use the moving ship as one of the fixed points of reference, plunge in the waves， the updated version of the astrolabe and quadrant, reduce the tendency, make mistakes, the most accurate and reliable of these early navigational instruments, work by measuring the angle IV. Transforming information Next you are going to read the text again to plete the chart below. SAILING THE OCEANS ■Using nature to help keeping alongside the coastline ■Using navigational instruments to help ●Using celestial bodies: North Star。 Sun。 Clouds ●finding longitude ●Using wildlife: Seaweed。 Birds ●Finding latitude: The Bearing Circle。 The Astrolabe。 The Quadrant。 The sextant ●Using the weather : Fog。 Winds ●Using the sea V. Closing down by reading more about sailing the oceans Sailing the oceans For thousands of years, people have been sailing across the oceans and around the world. Knowledge of ocean currents and wind patterns has allowed people to reliably reach their destinations even after crossing huge expanses of open ocean. In this photograph, a sailboat uses wind and currents to move among the islands of Micronesia. Before modern navigational techniques were developed, navigators in the South Pacific relied on stick charts to indicate island locations relative to winds and currents. Today, racing sailboats is a sport, and teams test their skills by racing around the world. Navigation now relies on satellites, but knowledge of wind patterns, ocean currents, and potential obstacles in unfamiliar waters is still essential for sailing. In this investigation, you39。ll plot a course for racing around the world in a sailboat. You39。ll explore some of the obstacles you might encounter on your route。 then you39。ll have the opportunity to r