user: Read the following article and select the best answer. Article: It's a sure sign that summer is over and winter is on the way -- leaves that were once deep green turn red, yellow and bright orange. It happens every autumn. But did you ever wonder why? The leaves start changing color when the nights start getting longer and the temperature starts getting cooler. Some scientists think that as the number of daylight hours _ the leaves stop making chlorophyll which makes plants green. The reason is that the process of making chlorophyll requires sunlight. But according to horticulture   educator Susan Rose from Colorado State University, it turns out leaves don't really change color at all. "The fall colors are actually there all along," she said. "But they are covered by the green chlorophyll. As the chlorophyll stops being produced, the other colors can shine through." The kind of color that the leaves are going to change to is determined by the plant's genetic   background. In some places, the leaves start changing color in September -- before autumn even officially begins. In other places, they don't change until late October or even November. Some scientists say the leaves have been changing color later than usual in recent years. And they think global warming has something to do with that. In one study, researchers found that the growing season in the Northern Hemisphere was nearly a week longer, on average, in 2008 than it was in 1982. And a professor from Harvard University found that the leaves, west of Boston, Massachusetts, are changing color about three days later than they used to. However, other scientists disagree with the global warming theory. Susan Rose said the leaves in her part of Colorado are changing "right on schedule." But the leaves in other parts of that state are running a little late. "The lateness in the mountains may have something to do with the really warm late summer and early fall," she said. "But I'm afraid that's just a guess." Question: Scientists guess leaves change color later than usual probably as a result of   _  . - genetic background - dry weather - global warming - low temperature
global warming

Read the following article and select the best answer. Article: A study made by University of Sussex found that men and women who frequently used several types of technology at the same time had less grey matter in a key part of the brain . The researchers said : " Simultaneously , using mobile phones , laptops and other media devices could change the structure of our brains . " Worryingly , the part of the brain that shrinks is involved in processing emotion . The finding has linked multi-tasking with a shortened attention span , depression , anxiety and lower grades at school . The researchers began by asking 75 healthy men and women how often they divided their attention between different types of technology . This could mean sending a text message while listening to music and checking email , or speaking on the phone while watching TV and surfing the web . The volunteers were then given brain scans which showed they had less grey matter in a region called the anterior cingulated cortex ( ACC ) . The findings held even when differences in personality were taken into account . The study , published in the journal PLOS ONE , is the first to make a link between multi-tasking and the structure of the brain . Researcher KepKeeLoh said : " Media multi-tasking is become more popular in our lives today and there is growing concern about its impacts on our cognition and social-emotional well-being . " He added that more researches are needed to prove that multi-tasking shrinks the brain . This is because it is also possible that people with less grey matter in the ACC are more likely to use lots of devices simultaneously . Scientists have previously described brain structure can be altered on prolonged exposure to new environments and experience . Other studies have shown that training - such as learning magic or taxi drivers learning the map of London - can increase grey matter densities in certain parts . Question: What's the purpose of the passage ? - To inform people of the findings of a research . - To stress the importance of grey matter in our brain . - To advise people to do more training about our brain . - To warn people of the possible danger of media devices .
To inform people of the findings of a research .

Read the following article and select the best answer. Article: Dear Daughter,     As we drove off from Columbia, I wanted to write to tell you all that is on my mind. First, I want to tell you how proud we are. Getting into Columbia is a real testament   of what a great well-rounded student you are. You should be as proud of yourself as we are.     Your college years will be the most important of your life. It is in college that you will discover what learning is about. This will be the period when you go from teacher taught to master inspired, after which you must become a self-learner. So do take each subject seriously, and even if what you learn is of no practical use in real life, the learning skills you get will be something you will value forever. Follow your passion in college. Take courses you think you will enjoy, don't be bothered by what others think or say, but make up your own mind. Most importantly, make true friends and be happy. Don't worry about their hobbies, grades, looks, or even personalities. Start planning early what you'd like to do. Where would you like to live? What would you like to learn? I think your plan to study fashion is good, and you should decide where you want to be, and get onto the right courses. I will always be there for you, but the time has come for you to be in the driver's seat--this is your life, and you need to be in control. Being in control feels great. Try it, and you'll love it! So please treasure your college years -- make the best use of your free time, become an independent thinker in control of your destiny, and learn through your successes and challenges. May your years at Columbia be the happiest of your life, and may you grow into just what you dream to be. Love Dad & Mom        (Excerpt from Kai-Fu Lee's letter to his daughter) Question: We can read between the lines that   _  . - Dad has a strong love for his daughter - Dad is very strict with his daughter - Dad always worries about his daughter - Dad is much concerned about his daughter's health
Dad has a strong love for his daughter

Read the following article and select the best answer. Article: I was at the post office early that morning, hoping to post a letter at the start of a busy day. Instead, , I found myself standing in a queue that went all the way into the hallway.I had never seen so many people there on a weekday. The queue moved very slowly.My patience ran out and I got angry. When I got to the counter finally, I finished my business quickly and briefly, and then walked past the queue that was now extending past the front door. Thinking I was going to be late for my dentist  appointment, I was scowling   as I headed into the parking lot. A woman was coming across the lot in my direction.She was walking with determination, and each step sounded very heavy.I noticed that she had a scowling on her face. Her body language said that she was having a really terrible day.My anger disappeared.I wished I could wrap her in a hug but I was a stranger. So I did what I could in a minute before she hurried past me-I smiled.In a second everything changed.She was surprised. Then her face softened and her shoulders relaxed.I saw her take a deep breath.Her pace slowed and she smiled back at me as we passed each other. I continued to smile all the way to my car. Wow, it's amazing what a simple smile can do.From then on, I became aware of people's expressions and my own, the way we show our feelings.Now I use that awareness in my everyday life to let it remind me that when facing the world, I can try a smile. Question: What can be inferred from the text? - The woman is a friend of the writer's. - The woman's spirits lifted because of the writer's smile. - The writer is good at hiding her feelings. - The writer was in time for her appointment.


assistant: The woman's spirits lifted because of the writer's smile.