Parkour (跑酷) is a sport which trains people to deal with any physical obstacles in their path. It is not a competition but a physical training. A person joining in parkour is called traceur. Traceurs run along a path and use only their bodies to deal with obstacles in the most efficient way. Parkour pays more attention to efficiency, 【小题1】(make) it different from the similar practice of free running. Parkour 【小题2】(common) includes running, jumping, climbing, rolling and other similar types of physical movements. Many teenagers think that parkour is quite【小题3】cool sport. They have great interest in it.

The 【小题4】(invent) of parkour can’t 【小题5】(give) to one person because many people have worked on it. A French officer developed the earlier form of parkour. The term “parkour” was first introduced by David Belle and Sebastiar Foucan in the early 1980s. 【小题6】that time, they were two teenagers. This sport【小题7】(become) more popular in the 1990s when many films were made on it.

【小题8】makes parkour different from other sports is its power to bring people together. It allows traceurs to forget the【小题9】(society) and other problems, and makes a large group work and grow together instead of competing with each other. People can benefit from parkour as it can make them stronger. Still, it also influences one’s thought process by improving self-confidence and critical-thinking skills. In this way, parkour allows one to deal with 【小题10】(difficulty) in daily life if he or she deals with them through parkour.

“Time waits for no man”—or so the saying goes. We can’t stop time and we can’t control 【小题1】, although sometimes, in our minds, we think time flies. But if this year 【小题2】 particular feels like it’s passing more quickly than others have done, there could be a scientific 【小题3】 (explain).

Of course, we know a year is usually 365 days long. Clever scientists calculated this a long time ago. They also worked out that every four years, we need an extra day 【小题4】 (call) a leap year to keep our calendar in sync (同步). But 2021 isn’t one of those years, and yet it’s not behaving like 【小题5】 normal year. Scientists have done the math and discovered the Earth is moving faster than it ever has in the last 50 years, 【小题6】 means that 2021 is going to be the shortest year in decades.

Apparently, this is 【小题7】 the Earth is spinning faster, quicker than it has done in decades, and the days are therefore shorter. But they are only short by a tiny amount—around 0.05 milliseconds—so don’t panic if you haven’t noticed! However, long-term these milliseconds add up. Graham Jones from Time and Date told The Independent newspaper: “If the Earth’s rotation continues to 【小题8】 (quick), we may at some point require a negative leap second. If this happens, our clocks would skip a second 【小题9】 (keep) up with the hurrying Earth.” Since 1972, 27 leap seconds 【小题10】 (add) to our time.

Why do we dream？Scientists aren't completely sure,and they have diverse【小题1】 (idea)．Dreams might be a side effect of memory making.When you sleep,your brain sorts through everything 【小题2】 happened during the day，trying to link new experiences to old memories.As it 【小题3】 (connect) things，your brain turns them into a story,and you get a dream．