C．the scientific study of natural objects in space

　　D．the theories developed by scientists of old times

　　3．Copernicus developed his theory ________．

　　A．using various telescopes

　　B．based on Aristotle's beliefs

　　C．through observations and reasoning (推理)

　　D．under the encouragement of his friends

　　4．The writer of the passage tells us that ________．

　　A．Copernicus did not tell about his discovery until the day of his death

　　B．for many years Copernicus dared to do nothing openly against the Church

　　C．pushed by his friends Copernicus decided to write a book in May 1543

　　D．shortly before he got back to Poland Copernicus started to work for the Church

　　B

　　I ran into a local store today to pick up a few things. With an important meeting to attend, I was in a hurry , so I didn't take a cart (手推车) on my way inside. As I walked between the shelves in the store, I passed by a young couple and their baby. I continued going through the store, picked up a few items I needed and ended up standing behind this couple in the checkout line.

　　While waiting, I noticed that the young father was holding his money tightly and nervously. The young mother was carrying a baby in her arms and asked the cashier (收银员) for a job application.

　　When the total was rung up, they had to pick items out of their cart because they didn't have enough money. But all their items were basic necessities (必需品) that they needed most. It just broke my heart to watch the couple try to think about what they could do without. However, they were able to whittle_down their items and paid the bill with the money that they had.

　　After they left, I quietly asked the cashier to add those items to mine. The cashier rang everything up, and then got me a shopping cart. We put in their items and I hurried over to their car. "This is for you，" I told them.

　　The young father just looked at me with such appreciation and thanked me. I will never forget the expression in his eyes. As I was getting into my car, they drove over. The young mother said, "Miss, thank you so much."

　　Tears welled up in my eyes - as they are again now, while I write this. "You are so welcome. Pay it forward some day，" I replied.

　　5．The underlined phrase "whittle down" in Paragraph 3 probably means "________"．

　　A．add to　　　　　　B．break down

　　C．cut down D．pay for

　　6．The author felt ________ to watch the couple taking some items out.

　　A．sad B．angry

C．excited D．interested