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  3. Concrete Another thing to remember in connection with concrete is that you are not allowed very much leeway for errors in e

Concrete Another thing to remember in connection with concrete is that you are not allowed very much leeway for errors in e

admin2010-02-17  66
问题                              Concrete
     Another thing to remember in connection with concrete is that you are not allowed very much leeway for errors in either measurements or location. Once you have a solid mass of concrete set in place, it is going to stay there. You have a difficult job ahead of you if you try to remedy a mistake. Make very sure, before you fill the form, that everything is where and how you want it.
     There are numerous rules regarding the proper mixing handing, and finishing of concrete, but the essential one concerns the amount of water to use. The less water in the mix, the less the finished job will shrink. The less water used, the harder and more enduring the job after it has set.
     The amateur concrete worker is plagued with two desires. One is to use enough water to have the concrete nice and soft and easy to push around. You have been warned against that. The second is to take off the wooden forms too early, to see what the job looks like. That is really fatal. If the forms are stripped off too soon, while the concrete is still green, two things are likely to happen--you are almost sure to break off corners or edges, and you are likely to cause a major crack or defect in the body of the work. An excellent rule is to wait until you are sure the concrete is properly hardened, and then wait another day before removing the forms.
In mixing concrete, one of the desires the amateur must resist is to ______.
选项 A、break off a corner to see if the "green" has gone
B、leave the form on too long
C、strip off the forms a day after the concrete has properly hardened
D、use too much water
答案D
解析 参见第二、三段。
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