3 . How long can human beings live? Most scientists who study old age think that the human body is ________ to live no longer than 120 years. However, 110 years is probably the longest that anyone could hope to live —— if he or she is ________ healthy and lucky. Some scientists even say we can live as long as 130 years! Yet, our cells simply cannot continue to reproduce ________. They wear out, and as a result, we get old and ________ die.

Even though we can’t live forever, we are living a ________ life than ever before. In 1900, the average American life span (寿命) was only 47 years, but today it is 75 years!

When does old age begin then? Sixty-five may be out-of-date as the ________ line between middle age and old age. After all, many older people don’t begin to experience physical and mental ________ until after age 75.

People are living longer because more people ________ childhood. Before modern medicine changed the laws of nature, many children died of common childhood ________. Now that the chances of dying ________ are much lower, the chances of living long are much higher due to better diets and health care.

On the whole, our population is getting older. The ________ in our population will have lasting effects on our social development and our way of life. Some people fear such changes will be for the worse, while some see ________, not disaster, many men and women in their “golden years” are healthy, still active, and young in ________ if not in age.

As the society grows old, we need the ________ of our older citizens. With long lives ahead of them, they need to ________ active and devoted.

4 . Last year,I met with a major accident.This accident totally changed the_______I used to look at things in my life. Like every day,it was time for my office for which I used to go_______a two wheeler vehicle.And that day I was not in the_______to wear the helmet.It’s very_______to ride a two wheeler in India and_______most of the Indians are ignorant about is wearing a helmet. And it was a _______for me too to wear a helmet every single day.

So I was riding the vehicle at an average speed of 30-40 mph when I thought to go_______of a scooter（小型摩托车）being slowly ridden (on the left end of the lane) by a middle-aged man in parallel. The only_______here was the wrong timing. The man without any hint or even looking at the back to check if any vehicle was approaching, _______ with his hand and immediately took a right turn to cross the street.

Unfortunately, just a second or two before this I had ________my vehicle to overtake the man. 3 seconds after, I knew our vehicles would bang as we were in a ________distance. In the very next moment, we along with our ________skidded for some distance.I got hit on the road directly on my back.It was a terrible jerk and the________developed pain gave me a serious sickening feeling. But for that moment I could only think about two things.“What would have happened if I hadn’t worn a helmet today?”“Was________person alright”?

Thankfully, the man was all night________he too was wearing the helmet.

That split second________of wearing the helmet changed my entire life,and turned this________accident into a minor one.I really thank myself for the decision I________that day. After this incident, I________myself I will always wear a helmet in any condition.This idea may not seem important to many of us, but it saved my life and the biggest of all, it made me realize how important small acts can ________to be!