Nowadays, lots of students in Shenzhen complain that they have too much homework. Because of this, they feel unhappy about learning at school. According to a survey, a pupil has to spend two hours finishing the homework every day. It usually takes three hours for a middle school student and four hours for a high school student to finish the homework every day. Students in Grade Nine often do their homework until midnight. And all of them have to get up at as early as six o’clock the next morning.

Mr. Li, a doctor in a hospital, told me yesterday, “Half of the students in Shenzhen are sub-healthy(亚健康的). The lack (缺乏) of sleep makes them tired and their health is becoming poorer and poorer.” Many parents worry about this.

Do you have enough sleep? With so much homework to do, it’s often difficult to get the rest you need. But you need to try, because sleep keeps you healthy and it stops you getting fat. Recently, a group of US scientists did a study among some kids between 8 and 13 years old.

The study found that if kids sleep for just one more hour each day, the chance of their getting fat is cut by about 30 percent.

Why? When people don’t get enough sleep, they become tired. When they are tired, they don’t exercise enough. Also, kids like snacks. If they are awake one or two more hours each day, they have more time to eat snacks or other unhealthy foods.

So, how much sleep should kids get? Scientists say it is better to sleep 10 to 11 hours a night for kids 5 to 12 years old. For older kids, eight to nine hours will work.

Eating or drinking on the subway has long been a contentious (引起争论的) problem in China. While many people have expressed disagreement about the smell of food and litter in train cars, quite a few also support the right to eat snacks during long trips to work or school.

The discussion finally arrived at its end when the Ministry of Transport introduced a new rule. The new rule bans passengers nationwide from eating or drinking in subway cars, with exceptions for babies and people with certain medical conditions. The policy came into effect on April 1, 2020.

Before the nationwide fight against subway snacking, a few cities, including Beiiing, Shenzhen and Nanjing, introduced similar rules banning passengers from having food and drinks in subway cars.

Zhang Han, a 26-year-old government worker, recalled that she was recently on a subway in Nanjing when she saw woman passenger fined for eating snacks. “At first, I did not know about the rule and felt sorry for the girl named Wei Hua,” she said “Most people, including me, didn't pay attention to such a food ban before.”

Now that a national ban is carried out, she said she supported the idea. “The subway car is a public space with poor ventilation (通风). No food should be allowed, whether it gives off a strong smell or not.”

For those in Hubei Province, it is much harder to challenge the long tradition of eating, including inside a subway car.

“The food ban doesn't fit local habits,” said Chen Xiangru, a native of Wuhan. “For many years, we've been having hot dry noodles, while walking, riding a bus, taking a taxi or even on boats. I personally won't be bored with the smell of food on the subway as I'm already used to it,” Chen said.

Jiang Ruoxi is a college student from Wuhan. He takes a softer opinion in the discussion. He suggests that the government offer some leeway (回旋余地) for passengers rushing between home and workplaces in a fast-paced city like Beijing or Shanghai.