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.

For the first time, scientists have grown plants in moon soil (土壤) collected by NASA's Apollo astronauts.

The scientists had no idea if anything would grow in moon soil. They wanted to see if it could be used to grow plants. Robert Ferl of the University of Florida was surprised with the results. "Plants actually grow in moon soil," he said.

Ferl and other researchers planted thale cress, a small flowering plant, in moon soil. The good news was that all of the seeds (种子) grew. The bad news was that after the first week, they grew slowly. Most of the plants ended up small and not fully developed.

Scientists found that the longer the soil was on the moon, the worse the plants seemed to grow. The soil collected by the Apollo 11 was the least helpful for growth. It was a couple billion years longer. One solution might be to use younger soil on the moon, like lava (火山岩浆), or put in some special nutrient (营养物) mixtures.

Only 382 kilograms of moon rocks and soil were brought back by the six Apollo groups that landed on the moon. Early last year, NASA finally gave out 12 grams of soil for the planting experiment (实验).

The Florida scientists hope to reuse their moon soil later this year, planting more thale cress before possibly moving on to other plants.

A scientist said, "Growing plants is a big step forward. The real next step is to go and do it on the surface of the moon."