Hot air balloons operate on the very basic scientific principle that hot air rises. Some people practice ballooning as a sport.【小题1】 Generally speaking, hot air balloons are quite safe.

Before examining the safety of hot air balloons, it may help to understand how they work. Each balloon has a large bag called an envelop, attached to a basket In order to get enough lift, the air in the bag is heated with the help of flame. 【小题2】 When the flight is over, the pilot slowly lets out enough air to allow the balloon to drop to the ground.

【小题3】 Typically, pilots choose the early morning hours to fly, since wind speeds are still low. Low wind speeds make riding in hot air balloons much safer, and the flights are more enjoyable.

The weather is the most important concern in hot air balloon safety. High winds and extreme weather such as rain and snow are potentially dangerous. 【小题4】 Good pilots also always check their equipment before beginning a flight and they often carry backup tanks of fuel and other equipment for safety.

Generally, pilots who want to fly hot air balloons must get a pilot’s license. 【小题5】 But in many countries, there are specific course and examinations which pilots must take to handle these types of aircraft. A private license allows a pilot to fly with a few friends, while commercial license permits a pilot to fly larger balloons.

Balloon rides can be great fun, and they are very safe as long as passengers follow the directions of the pilot.

Is there a single word that motivates us more than “weekend”？ It's like the promise of a sweet hereafter following what seems like a lifetime of toil (劳累). It's the spring in our step that gets bouncier with each passing day - until by Friday, we're practically bumping our heads against the ceiling.

The trouble is that the weekend is a rip-off. You think you're getting 48 hours of unconditional downtime, but reality takes a discount. In fact, it takes most of Sunday. That's when anxiety comes creeping in and another countdown begins: 12 hours until Monday. Sure, weekend is free time. But the mounting stress of an incoming Monday can erase any joy you might get from a Sunday evening.

That feeling is so common among the Monday-to-Friday crowd, there's even more than one name for it: the Sunday Scaries, or Sunday Fear Syndrome. Going from a countdown to the weekend to a countdown to Monday can be difficult. Even Monster.com - a website that specializes in yoking humans to the Monday-to-Friday cycle -admits it's a problem. In a survey, Monster found that 76% of Americans have “really bad” Sunday night blues.

For most people, Sunday is no holiday at all. It may all come down to the same problem: We can't stop thinking about tomorrow. Even worse, we may develop some downright unhealthy coping strategies for that transition from weekends to Monday. Some might resist - staying up late, milking every minute of a fleeting Sunday in the form of mind-numbing distractions.

But why should Monday cast such a long and fearful shadow on our lives? Maybe it's because the counter is reset, and the weekend, or happiness, seems at its furthest point. If, like most of us, you have a tolerable job, but don't much like the whole idea of working, there are plenty of ways to make Mondays a little less stressful. Most importantly, don't leave any unsettled Friday business hanging over the weekend. So, clear the decks and tie up loose ends.