咖啡鞣酸具有较广泛的抗菌作用，其结构简式如下所示：

关于咖啡鞣酸的下列叙述正确的是

阅读下面文字，完成小题。

    亲贤臣，远小人，此先汉所以兴隆也；亲小人，远贤臣，此后汉所以倾颓也。先帝在时，每与臣论此事，未尝不叹息痛恨于桓、灵也。侍中、尚书、长史、参军，此悉贞良死节之臣，愿陛下亲之信之，则汉室之隆，可计日而待也。

    臣本布衣，躬耕于南阳，苟全性命于乱世，不求闻达于诸侯。先帝不以臣卑鄙，猥自枉屈，三顾臣于草庐之中，咨臣以当世之事，由是感激，遂许先帝以驱驰。后值倾覆，受任于败军之际，奉命于危难之间，尔来二十有一年矣。

    先帝知臣谨慎，故临崩寄臣以大事也。受命以来，夙夜忧叹，恐托付不效，以伤先帝之明，故五月渡泸，深入不毛。今南方已定，兵甲已足，当奖率三军，北定中原，庶竭驽钝，攘除奸凶，兴复汉室，还于旧都。此臣所以报先帝而忠陛下之职分也。至于斟酌损益，进尽忠言，则攸之、祎、允之任也。

（节选自《出师表》）

用图所示的刻度尺来测金属块的长度，下列测量结果正确的是（   ）

2017年底，网上流传这样一段视频：一对外国老夫妇在海边拍摄风景照，无奈由于站立太久而深陷淤泥。一名中国渔夫见状，首先将他们身上的背包和摄影设备拿走，目的是减小他们对淤泥地的____力，然后渔夫无论是拖、抱、拽都无法使他们脱离淤泥；最后渔夫平趴在淤泥地上，他们撑着渔夫的身体才爬出了淤泥。渔夫平趴在淤泥地的目的是：增大人体与淤泥地的接触面积，以减小人体对淤泥地的____，使被困者脱离险境。

阅读短文，根据首字母提示填写单词。

      There is nothing more i____ to life than the sun. W____ the sun, all living things on the earth would die. The sun is a star. In the sky there are t____ of stars like the sun. They are as large as the sun and as hot as the sun. At night you can see many stars, but in the day you can o____ see one star-- the sun.

      The sun is much n____ to us than any other star. That is w____ it looks the biggest and brightest of all the stars. The distance (距离) of the sun from the earth is as m____ as 150,000,000 kilometers. Most stars are thousands of light-years a____from the earth.

      Do you know what a light-year is? N____ in the world travels faster than light. It travels 300,000 kilometers per second. And one light-year is the distance that light can travel in one y____.