Suppose you are going to Boston,and you have never visited the city before.​If someone tells
you about the interesting places in the city,you 15 to get some ideas of what you will see,but don’t have a 16 idea of where these places are or of how to find them.However 17 someone has a map of the city and 18 you the main roads and buildings,you may say,“Oh,now I see.I can find my way with 19 trouble at all”.Working in math is somewhat（有點(diǎn)兒） like trying to find your way 20 a new city.Perhaps the words may tell you some information and you have 21 it,but you can’t see any clear road 22 the answers.
Maybe you need to have a kind of map of the main roads in maths 23 you find your way.Explore what lies in maths,and try your best to find the main roads.They will 24
you to the answer.If you can find the “map”,the maths problems will be easily worked out.
15.A.begin B.like C.learn D.decide
16.A.clever B.clear C.strange D.wrong
17.A.if B.though C.whether D.since
18.A.helps B.gives C.passes D.shows
19.A.not B.no C.some D.much
20.A.of B.to C.in D around
21.A.thought about B.heard about C.written down D talked with
22.A.with B.for C.of D to
23.A.help B.to help C.helps D help with
24.A.keep B.send C.lead D.ask