Exercise has a range of health benefits. However, some people believe that     1     if some exercise is good, more is always better, so they tend to exercise for a long time without stopping. For example, some people go jogging for several hours at a time because of the step-counting smartphone apps.     2     还有些人周末连续锻炼数个小时 to make up for their lack of exercise during the weekdays. Habits like these put stress on the body, and if maintained over the long term,     3     they can be a serious health risk.

Generally speaking, aerobic routines that last over 100 minutes have a certain health risk. On the other hand,     4     they should not be shorter than 10 minutes. If you do exercise for only a few minutes, you may not be working out long enough to see any benefits from it. When you exercise, aim for the daily average of 30 to 60 minutes.     5     这将会防止你受伤. Moreover, it will ensure that the exercise you do has a positive effect on your physical health.

The day began like any other on Goldshore Beach. People were walking, running or simply sitting on the sandy beach, enjoying the warm sea air     1    and the soft wind that brushed their hair. Sabrina was one of the happy tourists     2    until she noticed something odd. “The water was like the bubbles on the top of a beer.” she later explained. “It wasn’t calm and it wasn’t going in and then out. It was just coming in and in and in.” Sabrina had just learnt about tsunamis in a Geography lesson． 她立刻想到了这一点     3    that these were signs of an approaching tsunami.

Sabrina was frightened，but she soon kept her head.她警告她的父母有危险,     4     though at first they just thought she was joking. However, Sabrina was certain that a terrible disaster was on its way     5    and kept asking her parents to talk to a safety officer, To her great relief, the officer immediately realized the coming danger. The beach was rapidly cleared of people, just before the huge waves crashed into the coast.