大学英语四级阅读理解练习 九

　　Questions 11 to 15 are based on the following passage:
　　Another thing to remember in connection with concrete is that you are not allowed very much leeway（余地）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, handling, 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 annoyed 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 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.
　　11.The best title for this passage would be ________.
　　 A) Rules for Working with Concrete
　　 B) Concrete and Its Uses
　　 C) Concrete, the Homeowner's Joy
　　 D) Concrete, a Test of Character
　　12.Two of the main thoughts in this passage are (1) preparation of forms for the concrete must be thorough, and (2) forms must be allowed to remain on long enough. The third main idea is _______.
　　 A) taking off forms beforehand will probably cause a crack in the body of the work
　　 B) trying to make changes after concrete has been poured is not recommended
　　 C) mixing concrete properly will make it very hard and strong
　　 D) using as little water as possible is recommended
　　13.In mixing concrete, one of the desires the amateur must resist is to ________.
　　 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
　　14.A human quality apparently not essential in someone who works with concrete is ________.
　　 A) carefulness
　　 B) patience
　　 C) self-control
　　 D) inventiveness
　　15.By the concrete being too "green", the author means that the concrete has ________.
　　 A) dried out
　　 B) hardened
　　 C) not yet cured
　　 D) not cracked