�、�.介、副詞填空
1.The voyages of travellers before the 17th century show that they were not________the mercy________the sea even though they did not have modern navigational aids.
2.On a clear day especially during the summer the sailors could use the sun overhead________midday to navigate by.
3.There is a special cloud formation which indicates there is land close________.
4.An early method of measuring speed involved throwing a knotted rope tied________a log over the side of the ship.
5.The number of knots that were counted________a fixed period of time gave the speed of the ship in nautical miles per hour.
6.________this way the ship could set a straight course even in the middle of the ocean.
7.________， it was awkward to use as one of the points of reference was the moving ship itself.
8.As the ship rose and plunged in the waves, it was________difficult to be accurate with any reading.
9.It works________measuring the angle between two fixed objects outside the ship using two mirrors.
10.This gave the seamen the local time and allowed them to find their latitude________sea.
答案 1.at;of 2.in 3.by 4.to 5.during 6.In
7.However 8.extremely 9.by 10.at
Ⅱ.單詞拼寫
1.This was a more p________and simplified version of the astrolabe.
2.So seamen could follow the birds to land even if they were o________and in the open sea.
3.This seems to have been the first and most useful form of e________which carried the minimum amount of risk.
4.Can you help me u________the files?
5.It was the first i________to measure the sun's position.
6.It was easier to handle because it was more p________.
7.However, it was awkward to use as one of the points of r________was the moving ship itself.
8.On a clear day especially during the summer the sailors could use the sun o________at midday to navigate by.
9.So the Vikings would observe the winds before and during their o________or return journeys.
10.Seamen used it to help i________the position of a stream or river when they were close to land.
答案 1.precise 2.offshore 3.exploration 4.update 5.instrument 6.portable 7.reference 8.overhead
9.outward 10.identify
