题目

为验证pH对唾液淀粉酶活性的影响，某学生设计了下表中的实验方法步骤。在同学们提出的下列评价中，不合理的是（   ） 实验步骤项目试管1试管2 1加入可溶性淀粉溶液2mL2mL 2加入新鲜唾液淀粉酶溶液1mL1mL 3    加入1 mol·L－1的盐酸溶液/1mL  加入1 mol·L－1的NaOH溶液1mL/  4置于37 ℃水浴中5min5min 5滴入碘液2滴2滴 A.缺少pH为6.8的对照组 B．都置于37 ℃水浴中可排除温度对酶活性的影响 C．检验实验结果的试剂选择是合理的 D．操作步骤设计合理  The old man in the picture is my grandfather. He is 70 years old, but he is very strong _________ healthy. What is his secret (秘密) to a healthy life? Let me __________ you. My grandfather loves ___________ a lot. Every day he walks in the park ___________ our dog, Dudu. Grandfather also loves playing ___________ . He usually plays it three ____________ a week, on Monday, Wednesday and Friday. He also ____________ table tennis matches on TV. Zhang Jike is his ___________ table tennis player. Grandfather has many other ___________ , too. He enjoys singing and dancing. He always has fun and is always ____________ . I think that is his secret.1.A. and B. or C. but D. so2.A. tell B. say C. talk D. speak3.A. swimming B. walking C. dancing D. running4.A. at B. on C. with D. in5.A. basketball B. volleyball C. tennis D. table tennis6.A. teams B. times C. matches D. clubs7.A. watches B. reads C. looks D. sees8.A. interesting B. wonderful C. favourite D. beautiful9.A. things B. dreams C. hobbies D. friends10.A. true B. cute C. free D. happy