题目内容
Do you have a good sense of direction? If not, please take
with you a compass. But if you forget to take a compass, you
can still find your way.
It's never a good idea to imagine that the family member
who was entrusted (委托) with the job of map-reading actually
knows where the family is. You can tell by the slightly
confused load on their faces that nothing on the ground seems
to match the map. Never mind. The sun is shining and it's still
morning.If you don't know the exact time, you can still find
out where south is, but you'll need to be patient.
①Find a straight stick and put it in the ground in a place
where you can mark its shadow.
②Try to position the stick as vertically(垂直)as you can.
You can check this by making a simple plumb line (铅锤线)
with a piece of string and weight. You haven't got any string?
OK, use a thread from your clothes with a button tied at the
end to act as a weight.
③Mark the end of the shadow cast by the stick.
④Wait approximately half an hour and mark the end of
the shadow again.
⑤Keep doing this until you have made several marks.
⑥The mark nearest the stick will represent the shortest
shadow, which is cast at midday, when the sun is highest in
the sky and pointing to the exact south.
⑦Pick a point in the distance along the line between the
shortest shadow and the stick.
⑧That point is south of where you are.
⑨Now you can turn the map, like you did before, and
find which way you should be travelling.
B. it is not easy to position the stick
C. it takes hours to make the marks
D. it takes about half an hour to make the marks
B. those who get lost
C. those who make compasses
D. those who do experiments
B. describing an activity in a lively way
C. testing an idea by reasoning
D. introducing a practical method
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