题干

关于显微镜操作及原理的叙述,正确的是(    )

A:在低倍镜下找到要观察的物像后,即可换上高倍镜观察

B:物像的放大倍数是指被观察物体长或宽的放大倍数

C:在低倍镜下,视野大观察到的物像也大

D:使用高倍镜时,先用粗准焦螺旋调节,再用细准焦螺旋调节

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答案(点此获取答案解析)

B

同类题2

阅读下面的文字,完成后面各题。

        中国古代的兵器据说有400多种,而适于近战的冷兵器的剑却是百兵之祖,铁兵之神,杀敌致胜的利器,英雄猛士的配饰,甚至是某种正义的人格和理想的象征。剑,又和“侠”结下了不解之缘,以致中国人以前对“剑侠”津津乐道。咏剑和咏侠成了中国文学的一种传统,而武侠小说也至今长盛不衰。

        唐朝建立以前,群雄逐鹿,李渊、李世民父子依靠刀和剑,杀出了一个新的王朝和时代,之后继续东征西讨,拓土开疆,兴文治而重武功,一时尚武好侠之风大盛。唐代虽是封建社会的黄金时代,但人间仍有种种不平,芸芸众生包括不甚得意的文人,也仍然向往侠义之剑。于是,继春秋战国之后,唐代又出现一个任侠好剑的高潮。俗话说:武人爱剑,文人爱砚。但唐代许多文人爱砚也爱剑,在唐人传奇里,虬髯客,昆仑奴,聂隐娘,红拂这些挺剑而起的男女侠客,纷纷出场亮相,我们至今仍可遥想他们那英雄或“英雄”的气概,而许多唐代诗人,则对剑与侠献上了热情的歌吟,如果以“剑之歌”为主题,请那些前后辈分不同的诗人前来,是可以开一个盛大的诗歌朗诵晚会。

        古代有各种各样的剑,载诸史籍的宝剑不下百种之多,如紫电、清霜、白虹、鱼肠等等,也有各种名号的侠,我们今日从金庸、梁羽生、古龙等人的小说中,仍可一窥端倪。游侠天涯浪迹,豪侠刀折公侯,义侠锄强扶弱,道侠盗亦有道,儒侠书剑风流,智侠能言善辩,怪侠狂放不羁,奇侠风云叱咤,女侠侠骨柔肠。如同阳光在光谱中可以分析出七彩,真正的武侠精神,集中表现了中华民族特别是贫民阶层的多种美德,凸显了民间社会规范人际关系的道德标准,如一诺千金,见义勇为,舍己助人,含冤解祸,轻死重义等等。又如一根红线贯穿百绯明珠,其中最为人所崇拜的则是不计私仇小怨而为国为民的侠士,这样,那些壮士或侠士手中的剑,就更是一柄令奸佞凶恶之徒或国家民族之敌见之魂飞闻之魄丧的正义之剑。

        现在是科学昌明,武库也日新月异的世纪,剑与侠早已成为历史。清人龚自珍早就说过:“吟到恩仇心事涌,江湖侠骨已无多。”何况是当今这个缺钙少铁人欲横流的时代?因此,锄强扶弱的侠肠,磊落正直的侠气,英雄豪杰的侠骨,更令人心向往之。而昔日被称为百兵之王的剑呢?对于有心之人,它仍然是生命精神的寄托,侠文化的象征,正义感的符号,然而,在现实生活中,它却已经退化为一种体育锻炼和舞蹈表演的器具。你要报效国家自然有许多新的途径与形式,而不必如孟郊《百忧》诗中所说的那样,“壮士心似剑,为君射斗牛。朝思除国难,暮思除国仇。”假如你真遭逢不平之事,那也不必10年磨剑而企图去削平天下的是非曲直,还是应该相信会有日益健全的法制和法律,如果法制与法律也有疏漏,而且有时也难免为小人掌控,小人戏弄,奸人歪曲,那就请相信人间的正道和天地的无私吧,昔日虎啸龙吟,今朝已经退至离手的剑,只能作壁上观的了。

                                                                                                                                                                  (选自李元洛《白刃明霜雪》)

同类题4

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。

    A Hong Kong Disneyland park admission ticket is your passport to a full day of magical adventures. Learn the ways to buy your tickets now.

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Ticket Type

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    Purchase 2 Park Tickets at one of the following locations and receive a FREE limited-edition Disney gift:

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    As a hotel Guest of Hong Kong Disneyland Hotel or Disney’s Hollywood Hotel, Park tickets are reserved for your purchase at front desk. Open daily from 9:00 am ---- 8:00 pm.

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