题目

我们已经初步了解物质构成的奥秘，下列有关说法不正确的是A. 原子可以构成分子，也可以直接构成物质B. 原子通过得失电子形成离子，但离子不能变成原子C. 在化学反应中，原子的核外电子经常充当重要的角色D. 某原子中含有36个质子，则该原子核外含有36个电子 答案：【答案】B【解析】A、原子可以构成分子，也可以直接构成物质，正确；B、原子通过得失电子形成离子，离子也可以通过得失电子变成原子，错误；C、物质的化学性质与最外层电子数有关，正确；D、原子中质子数=电子数，正确。故选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.1.The underlined phrase “whittle down” in Paragraph 3 probably means “__________”.A. add to B. break down C. pay for D. cut down2.The author felt __________ to watch the couple taking some items out.A. angry B. sad C. excited D. interested3.It can be inferred from the passage that _________.A. the young mother didn’t have a job thenB. the young father felt so sorry to accept helpC. the cashier treated the young couple impolitelyD. the young couple bought something unnecessary4.The author’s main purpose in sharing the story is to tell us __________.A. what a great plan she madeB. to take a cart while shoppingC. to help those who are in needD. how to pick out basic necessities