题目

如表是豌豆杂交组合的实验统计数据 亲本组合后代的表现型及其株数 组别表现型高茎红花高茎白花矮茎红花矮茎白花 甲 乙 丙 丁 戊高茎红花×矮茎红花 高茎红花×高茎白花 高茎红花×矮茎红花 高茎红花×矮茎白花 高茎白花×矮茎红花627 724 953 1251 517203 750 317 0 523617 243 0 1301 499212 262 0 0 507 据表回答： ①上述两对相对性状中，显性性状为      、           ． ②写出每一杂交组合中两个亲本植株的基因型，以A和a分别株高的显、隐性基因，B和b分I am a psychologist. I first met Timothy, a quiet, overweight eleven-year-old boy, when his mother brought him to me to discuss his declining grades. A few minutes with Timothy were enough to confirm that his self-esteem(自尊) and general happiness were falling right along with them. I asked about Timothy’s typical day. He awoke every morning at six thirty so he could reach his school by eight and arrived home around four thirty each afternoon. He then had a quick snack, followed by either a piano lesson or a lesson with his math tutor. He finished dinner at 7 pm, and then he sat down to do homework for two to three hours. Quickly doing the math in my head, I found that Timothy spent an average of thirteen hours a day at a writing desk. What if Timothy spent thirteen hours a day at a sewing machine instead of a desk? We would immediately be shocked, because that would be called children being horribly mistreated. Timothy was far from being mistreated, but the mountain of homework he faced daily resulted in a similar consequence —he was being robbed of his childhood. In fact, Timothy had no time to do anything he truly enjoyed, such as playing video games, watching movies, or playing board games with his friends. Play, however, is a crucial part of healthy child development. It affects children’s creativity, their social skills, and even their brain development. The absence of play, physical exercise, and free­from social interaction takes a serious toll on many children. It can also cause significant health problems like childhood obesity, sleep problems and depression. Experts in the field recommend the minutes children spend on their homework should be no more than ten times the number of their grade level. As a fifth­grader, Timothy should have no more than fifty minutes a day of homework (instead of three times that amount). Having an extra two hours an evening to play, relax, or see a friend would soundly benefit any child’s life quality. 1.What does the underlined word “them” in the first paragraph probably refer to? A. Timothy’s parents.                                                        B. Timothy’s grades. C. Psychologists.                                                              D. The students. 2.What did the writer think of Timothy after learning about his typical day? A. Timothy was very hard­working. B. Timothy was being mistreated. C. Timothy had a heavy burden. D. Timothy was enjoying his childhood. 3.Which of the following statements best describes the writer’s opinion? A. Children should be allowed enough time to play. B. Playing board games works better than playing video games. C. The more they play, the more creative children will become. D. The depression caused by homework makes children unwilling to play. 4.According to the passage, how long should a third­grader spend a day doing homework? A. About ten minutes. B. No more than twenty minutes. C. No more than thirty minutes. D. About fifty minutes.