—Always. It's good for my health.

—Only a week.

— ________.

    Almost all people think exercising is good for us. But how often should (应该) we exercise? Five days week? Four days week? Is two days week 1? Luckily, the answer 2 the question is not difficult to find.

    We asked Shawn Arent, a scientist (科学家), about this question. He said that people should 3 every day. It really does great help to our 4 and health.

    Shawn also told us 5 more interesting "There is a big 6 between exercising two days a week and three days a week," Shawn said. "With three days a week, your body gets enough exercise and you want to do 7 activities to be healthier (更健康的). 8, with two days week, you don't get much change (改变). You just don't do it often enough, so you can't fully (完全地) 9 the fun of exercising.

    "For children and old people, it's a good start to exercise two days a 10 at first. But I still want them to exercise more after some time. Three to four days a week will be wonderful for them," Shawn said.

    It is Oct. 24. You pick up a bottle of milk. You see "Best Before Oct.23" on it. What do you do with it? Most people just throw it away. It's a big waste.

    The United Nations says that over one third of food goes to the trash. But 795 million people on Earth don't have enough to eat. To change this, people have come up with great ideas. After all, the best place for food is our stomachs, not the trash.

    Sharing food

    People say, "There's no such thing as a free, lunch." But they are wrong. Recently, "share fridges" have come to cities like Shanghai and Quanzhou, Quick meals, milk, cookies and cakes are staying in the fridges. It is just like your fridge at home. The food comes from families and shops nearby. And it is free for every passerby to enjoy! This great idea comes from the popular "food bank" practice.

We keep our extra money in a bank. In 1967， some people in the US wanted to do the same with food. They then set up the world's free food bank.

    In many people's eyes, expired( 过期的) food becomes junk. But a company from the UK thinks differently. There is a "Best Before Date "on the food bag. Before that date, the quality(质量) is the best. But after that date, the food can be still OK to eat.

    So, the Real Junk Food Project, a British company, gets such food from supermarkets and puts it in cafes again. They don't give the food a price. You can give whatever money you like. If you don't want to spend money, you can help work there.