第一步,将若干只正常的小鼠,平均分为A、B两组。观察并记录小鼠的活动状况。

第二步,给A组小鼠注射适量的胰岛素溶液,给B组小鼠注射等量的生理盐水。一段时间后,A组小鼠会出现四肢无力、活动减少等低血糖症状,B组小鼠活动正常。

第三步,在A组小鼠出现低血糖症状后,分别给A、B两组小鼠注射等量葡萄糖溶液。一段时间后,A组小鼠恢复正常活动,B组小鼠没有明显变化。

请回答下列有关问题。

战国时期使秦国逐渐强大起来的社会改革是（    ）

    An old man lived alone in his old house. He hardly ever went out．He wouldn't ____with others．One day， a little boy setting____knocked (敲)at the old man's door .The door slowly opened. “Uh，sir， would you like to buy a magazine?”The old man didn't say anything．He____stared(注视)at the boy．The boy looked inside and saw lots of dog sculpture(雕塑品)on the table．“Do you collect dogs?" the boy asked．“Yes，they are all my family．”Hearing this，the boy ____. and felt sorry for him．“I have a magazine here about dogs．It's perfect for you．”The old man was ready to close(关) the door and said，“No，I don't____any magazines．”

The boy suddenly had an idea．He had a dog sculpture， which did not mean much to____．After a while，the boy returned____a box．The old man shouted this time．“I told you no magazines!”“I bring you a girl．”The boy ____the box and handed him the sculpture．The old man got____because no one had given him a gift before．From that day on，the old man started going out of his house often．He and the boy because good____．The boy even brought his pet dog to visit me old man every week．