题干

一根绳子用去了
2
3
米,正好是剩下的
1
8
,这根绳子原来长多少米?
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同类题2

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阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项。

    You may not know a lot of people when you start high school. Even if you know some new students, you still feel nervous that you don't know any upperclassmen (高年级学生) and teachers. How are you going to make friends among this sea of unknown faces?

    Most high schools welcome new students before school actually starts. These are helpful not only because you learn your way around the buildings and get to meet some of your teachers, but also because you get to meet new students. That way, when you show up on your first day of school, you may already recognize a few familiar faces.

    When you talk to people, you'll probably find that a lot of them are feeling just like you. They're all new to the school and don't know what to expect. Talking about a common concern with your classmates can help you develop friendships.

    The work in high school is something freshmen are probably worried about. The work in high school builds on what you learned in middle school, giving you a more advanced knowledge of many subjects. So you may find you have more work to do or that it's a bit more challenging (有挑战性的). If you ever find your work too difficult, teachers can give you extra help.

    High school also has more activities after class than middle school, such as clubs, music and theater groups and sports teams. This is a good time to explore your interests and try new things.

    Middle school taught you the basics of academics, time management, and social skills while providing you with a little extra support and guidance. High school gives you the chance to learn how to be more independent (独立的) and responsible (有责任的).

同类题5

阅读下文,回答相关问题。

                                                                                              微妙的头发
        ①人们都有一头密密的头发,黑色的、金色的、褐色的,但很多人却只知道它与生俱来,不知道它生长的秘密、奇妙的特性、蕴含的丰富成份和非常广泛的用途。
        ②一般人有10万根头发,其生长速度为3天1毫米。人每天落发50—100根,同时又有大体相同的新发补充。头发含铜、铁、镍、钛、钼、铝、铬、锌、铅等14种元素,耐腐蚀,同等截面承受力为钢的1.25倍,200多根头发编成的辫子可吊起20吨重的物体。英国广播公司一次“创纪录”节目中,潘蒂兰小姐的一根头发竟承受了177.18克的拉力。人发拉断前可延展20%—30%,上述性能都是其它纤维难以具备的。
        ③在著名笔乡——日本广岛熊野町,头发被用以生产品种繁多的毛笔,其中最珍贵的是用新生婴儿头发制成的“胎毛笔”,每支售价一万至二万日元。设计师玛萨·海斯女士别出心裁用人发精编成各式时装,最低的售价也高达2.5万美元,有人甚至愿出百万美元高价认购其中的精品。
       ④直径60—70微米的每根头发,含有18种氨基酸。用毛发提取合成的精氨酸、胱氨酸已临床应用于医治肝炎及各种脱发症,组氨酸可治疗消化道溃疡,脯氨酸可治疗高血压,赖氨酸为儿童身体发育所必不可少。在捕鲸受到严格控制后,人发已日益成为生产氨基酸的重要原料。日本与印度不久前协定,在印度投资建造一座加工厂,年消耗1200吨毛发,产出80吨胱氨酸、24吨酪氨酸和1400吨含氨基酸的干粉,广泛用于制药、食品加工、化妆品和饲料工业。我国不少地区用人发作原料,制成初级产品出口创汇。
       ⑤最近几年,科学家又发现人发中含丰富的黑色素和角朊,是制造防晒油的高级原料。目前用人造原料制成的防晒油易引起皮肤过敏,而以人发为原料不仅不会造成过敏,还具有吸收紫外线光谱范围广、在强烈光照下不会变质等诸多优点。随着科学技术的发展,头发还将不断以更新的面貌,为世界提供巨大而奇妙的资源。