题目

区分羊毛织品和尼龙布最简单的方法是 (     ) A. 灼烧并闻气味    B. 观察外观 C. 放在水中比较柔软性    D. 手摸，凭手感区分 答案：【答案】A 【解析】 试题分析：羊毛的成分是蛋白质，尼龙的成分是聚酰胺纤维，区分它们的最简单方法是灼烧，蛋白质灼烧过程中有烧焦羽毛的味道，而尼龙没有，故选项A正确。 考点：阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中，选出可以填入的空白处的最佳选项，并从答题卡上将该选项涂黑。 You have waited 45 minutes for the valuable 10 minutes’ break between classes. But when the bell for the next class rings, you can’t   36   how quickly time has passed. If you are familiar with this   37  , you’ll know how time flies when you are having fun-and  38   when you are bored. Now scientists have   39   a reason why this is the case. Scans have shown that patterns of activity in the brain   40   according to how we focus on a task. When we are   41  , we concentrate more on how time is passing. And this makes our brains   42   the clock is ticking more slowly. In an experiment   43   by a French laboratory, 12 volunteers watched an image   44    researchers monitored their brain activity. The volunteers were told to   45   concentrate on how long an image appeared for, then   46   the color of the image, and thirdly, study both duration and color. The results showed that  47   was more active when the volunteers paid   48   subjects. It is thought that if the brain is   49   focusing on many aspects of a task, it has to  50  its resources, and pays less attention to the clock.  51 , time passes without us really   52   it, and seems to go quickly. If the brain is not so active, it concentrates its   53   energies on monitoring the passing of time.   54  , time seems to drag. Next time you feel bored   55  , perhaps you should pay more attention to what the teacher is saying! A．guess                   B．learn                      C．believe                   D．doubt A．view                    B．point                      C．scene                   D．experience A．drags                   B．stops                      C．backs                      D．gains A．thought over         B．made up                 C．suggested                D．come up with A．change                 B．develop                  C．grow                      D．slow A．sleepy                 B．bored                            C．excited                   D．active A．report                  B．think                      C．decide                    D．see A．produced              B．carried                    C．tried                       D．performed A．so                        B．when                      C．while                      D．but A．partly                 B．quickly                   C．how                       D．first A．remember           B．focus on                 C．forget                     D．tell apart A．the researchers    B．the experiment        C．the clock                 D．the brain A．much attention to                           B．more attention to     C．attention to many                                        D．attention to more A．busy                  B．likely                            C．ready                      D．sure A．focus                 B．gather                     C．reach                      D．spread A．However            B．Furthermore            C．Therefore                D．Finally A．recognizing        B．watching                 C．noticing                  D．counting A．enough               B．full                        C．right                       D．proper A．In fact                B．As a result                     C．For example            D．Instead A．in class               B．with work               C．in mind                  D．of lessons