6.Long ago,sailors sailed to faraway places without the ability to rely on modern instruments to lead the way.Still,many were able to sail across vast,uncharted oceans and arrive at their destinations safely.Why didn't more sailors get lost at sea?What kinds of equipment did they use to find their way?
In early sailing history,few maps were available.Sailors had to rely on memory and on written guides called pilot books.Pilot books offered sailors information about how long it took to get to certain ports and instructions about getting in and out of the ports.Pilot books did not offer much information about sailing far from land.
Later,sailors used maps,charts,and information from other explorers to plan their trips.Early maps and charts offered descriptions of islands and coastlines tht helped sailors navigate.Experienced sailors learned where harbors,fresh water,supplies,and riendly people might be found.They were also able to warn others about dangers.Some of the early navigation practices and equipment used on these ships proved to be quite trustworthy.Early sailors used a tool called the astrolabe (星盤) to figure out the positions of stars and the sun to determine their location.For centuries,sailors planned their routes,sailed,and recorded their progress using the North Star as their only reference.They also used patterns of wind and waves as directional clues.Even though ocean waves may look the same to inexperienced eyes,they have different shapes related to the depth of the ocean and their closeness to land.Sailors even found a way that clouds and seabirds could help them.
The sailors of yesterday relied heavily on their observations and studies of the sea.Although their techniques were simple,they were able to achieve great things during their adventures at sea.
28.According to the text,pilot booksA.
A.a(chǎn)re maps charted by other sailors
B.a(chǎn)re guides written by other sailors
C.offer descriptions of islands and ports
D.offer information about sailing far away
29.We know from the text that early explorers and sailorsD.
A.established the shipping network
B.invented many modern sailing tools
C.could locate all the ports and islands
D.shared information and offered warnings
30.What is Paragraph 4mainly about?D
A.How early sailors found their way.
B.The importance of early navigation.
C.The difficulty of sailing far from land.
D.What arly sailors found on their journeys.
31.What's the author's attitude towards the sailors of yesterday?C
A.Objective.
B.Sympathetic.
C.Praiseworthy.
D.Regretful.