题目

在平面直角坐标系xOy中，以原点为位似中心，线段AB与线段A′B′是位似图形，若A（﹣1，2），B（﹣1，0），A′（﹣2，4），则B′的坐标为__． 答案：【答案】(-2,0)【解析】设B′的坐标为，∵线段AB与线段A′B′是位似图形，且A（﹣1，2），A′（﹣2，4），∴位似比k=，∵点B的坐标是（-1，0），∴点B′的坐标为（-2，0）.More than 30,000 people went to the White House on Monday for the 136th Easter Egg Roll (复活节滚彩蛋). President Barack Obama and First Lady Michelle Obama held the event by inviting thousands of kids to color and look for eggs. The theme(主题) of the day was “Hop Into Healthy, Swing Into Shape.” It was part of the First Lady s“Let' s Move!”program to reduce obesity rates (肥胖率) among American kids. Mrs. Obama spoke to young reporters about her goal(目标) to get children to eat right and keep moving.“We are working to make sure that kids born today grow up healthy, learn how to have balanced meals, and get more physical activity into their lives,” she said.Mrs. Obama said she wants children across the nation to understand that "exercise isn't just hard work, it' s play. If you're running around with your dog, you're getting exercise. If you walk up the stairs, that's exercise. But if you're sitting in front of the TV or on a computer game, you're not exercising.”The First Lady said that for kids who have balanced meals most of the time, having a special snack, like chocolate, will not hurt. "And if you are active, you can splurge (挥霍) a little more," she said. Mrs. Obama’s favorite "splurge food" is French fries. But she balances her splurging by exercising almost every day. She loves to play tennis and she practices yoga.“A lot of kids look up to(敬仰) athletes, and I think it's important for athletes to share their good habits,” Mrs. Obama said. "Kids aren' t just going to wake up and be LeBron James. He's practicing and eating right and working out and training. Our athletes can be really good messengers to kids who look up to them — they can say to kids, ‘If you really want to be like me, then you really do need to eat your vegetables.’”【1】The purpose of the “Let’s Move!” program is to ________.A. help kids keep healthyB. train more young reportersC. encourage kids to eat more eggsD. invite kids to visit the White House【2】In Mrs. Obama’s opinion, exercise ________.A. can be fun to doB. means hard workC. should be done outdoorsD. requires special equipment【3】“Splurge food” is allowed to be eaten when ________.A. you don' t hurt yourselfB. you have a special snackC. you never eat French friesD. you eat right and stay active【4】What can we learn from the last paragraph?A. All kids want to be LeBron James.B. It is very easy to form good habits.C. Athletes can set a good example for kids.D. Kids like the messages the athletes give them.