"my camera scanning the sun" What does "scan" mean here? Patient as I was, after about 15 minutes, my camera scanning the sun and reviewing the shot I would eventually take, I grew frustrated. Was it too much to ask her to move so I could take just one picture of the landscape? Sure, I could have asked her, but something prevented me from doing so. She seemed so content in her observation. I didn’t want to mess with that.

"fall halfway down the track" It means that the runner falls on the ground in the middle of the competition or the runner falls behind other runners? Sports day might be necessary at a highly-competitive independent school, but not at a village primary school. For the children who can fly like the wind, sports day cause no problem. For those who are overweight or just not good at sport, it is nightmare（噩梦）. Even for those who enjoy running but fall halfway down the track in front of the entire school and their parents, it can prove a disaster.

How to understand "just as they are " in this sentence? "Many people find them beautiful just as they are" Have you ever watched a new building going up? The steel frame is built first. Then the glass walls are hung on the frame. When the building is finished，the frame does not show. The outside looks like windows without walls. The glass walls shine in the sun with no decoration. Many people find them beautiful just as they are. Does it mean: They are beautiful because the glass walls themselves are beautiful. They don't need any decoration.

Is this expression "How appropriate it is" commonly used? How to understand it in the following context? Plastic's toughness and flexibility represented a revolution in materials science during the 1950s and '60s. Decades later, however, plastic's very durability is raising questions about how appropriate it is for one-time products such as plastic bags, or short-lived consumer goods, used in the home for a few years and then cast into a landfill where they will degrade for centuries. What is the point of making something that lasts 1,000 years? I understand it is not appropriate for one-time products used for a few years and then thrown away to degrade for ages. I am just confused by the use of "how". Is it like the way "how many"or "how long" is used?

What does "build on "mean in this sentence? she built on a lifetime of spending time by herself as a reader She built "what" on a lifetime of spending time by herself as a reader? Jacqueline may have been hired for her name and for her social relations, but she soon proved her worth. Her choices, suggestions and widespread social relations were of both to the publishing firms and to Jacqueline herself. In the books she selected for publication, she built on a lifetime of spending time by herself as a reader and left a record of the growth of her mind. Her books are the autobiography she never wrote, Her role as First lady, in the end, was overshadowed by her performance as an editor. However, few knew that she had achieved so much.

How to understand" Nothing beats a good bite that bites back”？ My mom gave me some wise advice:”Nothing beats a good bite that bites back.” She was talking about her love for bitter-tasting food like rhubarb. Does "a good bite"here mean a good dish? then "bites back" must be a verb here, what does it mean?

What does "stand on one's head" and "down and under"mean in the following passage? Soil conditions made just perfect for roses turn out to be even more perfect for tomatoes．The daily watering coupled with full sun and regular fertilizing have turned the little plant into a tall bush．The cage I placed around it as the plant grew has long since disappeared under the thick leaves． Now the task I face in harvesting the fruit is two fold：First, I have to find the red ones among the leaves, which means I almost have to stand on my head, and once found I have to reach down and under, pick the tomatoes and withdraw my full fist without dropping the prize so dearly won． 1. does "stand on my head" mean I stand upside down? I don't get it. Why she needed to pick up tomatoes in such a strange position? 2. doesn't "down" and "under" have the same meaning? Or is it a phrase?

What does "Don’t leave before you leave."mean ? At 23, my career got going. I was midway through a master’s degree and had been hired as a part-time reporter for a finance website. I got a great one-month review and my boss asked if I was interested in staying with the company after graduation. 　　However, balancing graduate studies with work was challenging. To deal with it, I checked my real self at my office door. I came in to work, greeted my colleagues and listened more than I contributed in each morning meeting. The small team I worked with often seemed busy, so rather than giving ideas that might get turned down, I stayed back. 　　After four months, my boss called me into his office. The meeting was going well until he told me that despite the great work I had produced, the team had held a meeting and decided, “We don’t think it’s the right fit.” 　　I must have looked confused. “You’re ambitious, intelligent and will be very successful,” my boss said. “But you haven’t made enough of an effort to join the team. You lost the enthusiasm you showed in your interview. That won’t work long term, and if I could give you one piece of advice, it would be to let your guard down. Don’t leave before you leave.”

How to understand " I checked my real self at my office door."? At 23, my career got going. I was midway through a master’s degree and had been hired as a part-time reporter for a finance website. I got a great one-month review and my boss asked if I was interested in staying with the company after graduation. 　　However, balancing graduate studies with work was challenging. To deal with it, I checked my real self at my office door. I came in to work, greeted my colleagues and listened more than I contributed in each morning meeting. The small team I worked with often seemed busy, so rather than giving ideas that might get turned down, I stayed back. Does check mean "stop" here?