3．Compass
Find Which Direction Is South
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 wise idea to believe that the family member who was good at the job of map-reading knows where the family is．You can tell by the troubled look 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（a dark shape on a surface that is made when something stands between a light and the surface）．
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）．You haven't got one？OK，use a thread（线） from your clothes with a button（纽扣） tied at the end to act as a weight．
③Mark the end of the shadow cast（投射） by the stick．
④Wait about 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．
34．To find the direction，we have to be patient probably becauseC．
A．it is not easy to find a proper stick
B．it is not easy to position the stick
C．it takes hours to make the marks
D．it takes hours to mark the map
35．The passage would probably be most helpful toB．
A．those who draw maps
B．those who get lost
C．those who make compasses
D．those who do experiments
36．Which of the following pictures best shows the way of finding the direction of south？A
37．The writer presents this passage byD．
A．telling an interesting story
B．describing an activity in a lively way
C．testing an idea by reasoning
D．introducing a practical method．
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