Dr. Nate Lewis patiently adds a chemical to a machine in his laboratory. The chemical smells a little bit like rotten (变质的) fish. We know that because we have our noses to smell and know it. Dr. Lewis, however, wonders if his machine can smell the chemical, too. The machine is actually an electronic nose.

You might wonder why anyone would want to build an electronic nose. After all, if you want to smell something, you can just breathe in through your own nose. For example, it's common for someone to smell a bottle of milk to check if it has gone bad. But imagine if a person had to smell the thousands of bottles of milk that farms produce every day-all that milk would go bad long before the testing was done! The food industry uses electronic noses every day to test the foods for freshness.

There are millions of different smells in the world. How can our nose tell the difference between all these smells? Scientists know there are cells in our noses that act as smell detectors (探测器). They think that a certain    pattern of cells respond (回应) to every smell. Our nose creates a fingerprint for each smell using this pattern. Our brain understands all the odor (气味) fingerprints, Dr. Lewis's electronic nose works like the human nose to detect odor fingerprints.

The biggest difference, however, between human noses and the electronic noses that have been built so far is    the brain. We need our brains to explain each smell we meet. But the electronic nose can only identify the chemical makeup of a smell while our brain can decide whether something your nose smells is good or bad. "It doesn't know which smells it likes and which is terrible because it can't think." explains Dr. Lewis.

Dr. Lewis is working on how to make the electronic nose get smarter. Maybe someday fridges with electronic noses will tell you when food has gone bad, or your locker room will use them to remind you to wash your sports   clothes. There are many possible uses for a machine to take the place of the human nose. Every day scientists are getting closer to building a more perfect electronic nose.

"If you are not fat, you must be a thin man. ""For every minute of breathing, 60 seconds pass. ""Why do you say I am lazy? Obviously, I didn't do anything. "

Nonsense? Yes. These sentences look like they make sense, but they actually express little useful information. They are part of a recent Internet sentence-making craze called "nonsense literature(文学)".

"Nonsense literature" was originally invented by Internet users to make fun of the empty, fussy (过分讲究的) and redundant(累赘的) writing style often used by media and some famous people. Like any good Internet joke, it became a popular word game. Plenty of "nonsense" has been created. "Every time I don't know what to say, I don't know what to say. " "Listening to your words is like listening to words. "

Some even said that famous writers like Lu Xun used the style. For example, they said, Lu Xun once wrote: There are two trees in my backyard. One is a jujube tree, and the other is also a jujube tree. 

Is it true? Not really. Repetition in writing is not necessarily "nonsense literature". Lu Xun's writing on the jujube trees comes from a piece of his articles. If you have read it, as well as understanding his time of writing, you'd find these repeated lines are powerful, showing that the writer was frustrated by social reality.

Actually, "nonsense" and"literature" are two incompatible(矛盾的) words. Nonsense is silly and useless. It will soon be forgotten. But literature is written work considered to have artistic value. It is a spiritual treasure worth passing down.

Internet crazes like "nonsense literature" might make you laugh for a while.  ▲ . Don't throw yourself into it. Read some real literature. It will help us stop talking nonsense.

As a mountain, 1,642-foot Squaw Peak isn't that impressive. But its views attract many hikers（远足者）. Henry Grant, a college student at Ithaca College, was one of them.

While waiting for his mother one day in August, 2019, Grant watched other hikers enjoy the view. One hiker, dressed in pink, was looking over the lip of the cliff（悬崖）with her husband. 

When Grant's mother rejoined him, the two continued on their way. Suddenly, he heard something scaring: "Paula! Paula!" a man shouted crazily. Grant turned around quickly. ____

Several hikers immediately started looking for her, but their view was screened by trees. Uncertain they could help, Grant and his mother headed down the trail. But when he saw some hikers still searching, he decided to lend a hand. After promising his mother that he would be safe, he went on alone.

After 15 minutes of climbing over large rocks, pushing past bushes, and slipping（滑） down loose earth, Grant found a pink figure. The woman had fallen about 75 feet. Luckily, she was alive. 

"Paula! Paula!" Grant shouted. The woman didn't reply. She was badly hurt. Grant called the police to report her location. She kept trying to move, and every time she moved, she slipped a little more. Afraid that in her unclear state of mind she might fall off the rock to her death, Grant climbed on all fours up a tight, narrow path by digging into the earth with his fingers and feet until he reached Paula.

Paula was moaning, almost senseless. Grant gently put her hand in his, trying to keep her mind off the pain by keeping asking her questions: "Where are you from? Do you have kids?" Soon, they were joined on their perch（歇脚处）by another hiker named Simon.

About 45 minutes later, first rescuers（救援者）arrived. Paula and her husband were flown to a hospital. Five hours after the woman in pink had fallen, Grant was back on top of Squaw Peak.