题干

当显微镜镜筒下降,操作显微镜的人的目光注射的部位是               (   )

A:镜筒 

B:目镜 

C:物镜 

D:物镜与装片的距离

上一题 下一题 0.0难度 选择题 更新时间:2019-10-16 11:46:51

答案(点此获取答案解析)

D

同类题1

任务型阅读

    How to Become an Activist (活动家)

    Activists are people who see the need for change and devote their time to doing something about it.____If you are interested in it you can do so.

    ____This could be anything from a student club to a national organization (like the American Civil Liberties Union or the National Organizers Alliance). Most activist organizations offer different levels of involvement, so you can do whatever you feel most comfortable with, whether that means attending meetings and demonstrations or just donating a little money when you can.

    Volunteer your time. One of the best ways to make a difference is to volunteer your time. Reach out to organizations in your community that do work for your cause, and ask how you can help.

    Donate money or supplies.____If you can't afford to donate money to an organization that supports your cause, you may be able to donate other things they need, like clothing or canned food.

    Reach out to family and friends. Tell your family and friends about your cause, and invite them to get involved. If they are interested, share literature about your cause or just talk to them about what you have learned.____

    Promote your cause on social media. You can use social media to help keep your friends and followers informed about the causes you support.____Also, you can invite your friends to attend events or donate to fundraisers for your cause.

A. Take classes on issues related to your cause.

B. Join an organization that supports your cause.

C. They are driven by passion and a vision for a better future.

D. If you do volunteer work, invite them to volunteer with you.

E. Most activists or charitable organizations need resources to do their work.

F. Post useful articles and write about what you are doing to stay involved.

G. If you can't reach out to them in person, then try connecting to people online.

同类题4

阅读下文,回答相关问题。

                                                                                                      鹦鹉鱼的睡衣
      ①欧洲地中海生活着一种鱼,它色彩艳丽,脊背是紫红色的,体侧是玫瑰红色,胸部和腹部的鳍是淡黄色的,背鳍是灰黄色的,尾部镶白色的边,就像鹦鹉那样漂亮,所以人们叫它鹦鹉鱼。
      ②罗马和古希腊人特别器重这种鱼,把它当作珍品,这倒不是因为鹦鹉鱼长得漂亮,而是它们的团结互助的精神。据研究这种鱼的学者发现,如果鹦鹉鱼一旦不幸碰上了针钩,在千钧一发之际,它的伙伴会很快赶来帮忙,咬断钓鱼线,从危险中救出同伙。如果有的被鱼筐围住了,别的伙伴就会用牙齿咬住它的尾巴,拼命从筐缝中把它拉出来。所以,一般的渔民很难捕获到这种鱼。
      ③虽然鹦鹉鱼能够互相帮助,一般的危险奈何不了它们,可是,这并不等于鹦鹉鱼永远没有危险。因为鹦鹉鱼很怕死,常常在没有危险的时候也忧虑忡忡,它们想,白天遇到危险了,有同伴来救助,如果晚上同伴们都睡着了,谁来救自己呢?于是,鹦鹉鱼们想出了一种办法。它们每天傍晚都会给自己织一件睡衣穿,这样便确保了晚上的安全。
      ④它们织睡衣的方法像蚕吐丝作茧似的,从嘴里吐出白色的丝,利用它的腹鳍和尾鳍的帮助,经过一两个小时就能从头到尾织成一个囫囵的壳,这就是它们的睡衣。每天晚上,它
们睡在自己编织的睡衣里,确实能够防御敌人的侵害,并能安安静静地睡一晚。可是它们的睡衣织得太坚固了,第二天早晨要费很大力气才能把睡衣弄破,以便从里面钻出来。到了晚上,鹦鹉鱼再织一件新的睡衣穿在身上。
      ⑤有时候,鹦鹉鱼生病了,晚上躺在睡衣里,早晨想出来的时候,因为没有足够的力气钻破睡衣,这就麻烦了,时间一长它必死无疑。因为,鹦鹉鱼从不救助困在睡衣里的同伴,它们会认为同伴还在睡觉,不便打扰。
      ⑥所以,对于鹦鹉鱼来说,最大的危险不是来自外界的伤害,而是因为作茧自缚的自残。人类也拥有像鹦鹉鱼相似的一件睡衣,我们从来不缺乏互相帮助的精神,但却逃不脱作茧自缚的危险。                                                   

                                                                                                                                                                                (选自《意林》)