Film cameras and digital cameras work in a similar way. Film cameras After all, a film camera is basically a light - proof   box. It has a lens   system to focus light onto the film at the back of the camera. Let's suppose that we are outside on a beautiful summer day trying to take a picture of the family dog. We are using a film camera. We finally get the dog to lie still. You point the camera at him. What happens? Light goes into the camera lens and hits the shutter. In other words, nothing happens yet. Now let's say that the dog looks really cute and you decide to snap a picture. What happens? When you press the button, the shutter opens for a very short period of time. A small amount of light passes through and hits the film at the back of the camera. This creates an upside-down and reversed  image on the film. When you finish the roll of the film, you can take it to the photo shop to develop it and you will have a great picture of your dog! Cameras come with different lens lengths. Why does it matter? Many small cameras have shorter focal lengths, which means that there is a small distance between the lens and the place where the light focuses at the back of the camera. This gives you a large view of the area you are taking a picture of. Lenses with a long focal length show a smaller area but allow you to focus on distant objects and make them bigger. They are often called telephoto lenses. A good example of a long focus lens is one that is used by sports photographers to get photos of football players as if they were standing right beside them. Digital cameras In digital cameras, the light falls not on film but onto a sensor   called a CCD (Charge Coupled Device). This digitally converts  light and color into a digital information or pixels  . The CCD is the heart of any digital camera and usually the most expensive part ---- depending on how good it is. The main reason that sports photographers can get clear and big photos of players is that    _   . A) they use digital cameras B) the lens of their cameras is excellent C) their focus lenses are short D) their focus lenses are long
D

Mr. Grey was the manager of a small office in London. He lived in the country, and came up to work by train. He liked walking from the station to his office unless it was raining, because it gave him some exercise. One morning he was walking along the street when a stranger stopped him and said to him, "You may not remember me, sir, but seven years ago I came to London without a penny in my pockets, I stopped you in this street and asked you to lend me some money, and you lent me PS 5, because you said you were willing to _ so as to give a man a start on the way to success." Mr. Grey thought for a few minutes and then said, "Yes, I remember you. Go on with your story!" "Well," answered the stranger, "are you still willing to take a chance?" Mr. Grey liked walking to his office because   _  . A) he couldn't afford the buses B) he wanted to save money C) he wanted to keep in good health D) he could do some work on the way
C

Chicago's children's Hospital is the lucky receiver of a surprise $18million gift from Gladys Holm.She once was a secretary who never earned more than $15000 a year and never married.She lived alone in a small flat in Chicago,and was a volunteer at the Children's Hospital.She was called the "Teddy Bear lady" because she brought toy animals to sick children on her regular visits.But Miss Holm,who died in 1996 at the age of  86 ,was also a long-time buyer of stocks .Over the years,she saved money that rose up to $18 million ,which she left to the Children's Hospital .It was the largest single donation in the hospital's 115-year  history.The hospital president,Jan Jennings,was shocked when she heard the news "when Miss Holm's lawyer called to tell me how much that money was,I asked him to repeat it ,since I was certain I had misheard." Why did Gladys Holm fell so strongly about the Children's Hospital? Jennings said the hospital first touched Miss Holm's heart nearly 50 years ago,when doctors there saved the life of her friend's daughter.She never forgot the happiness she felt all those years ago. Holm's gift will be devoted to heart disease research.People at the hospital said they regretted that they couldn't thank Miss Holm for the surprising gift. Why did Jan Jennings ask the lawyer to repeat what he said? A) she never expected Miss Holm would donate anything. B) she want to make sure who Gladys Holm was C) she had seldom received donations before D) she thought there was a mistake

D