题目

The Marches’ house was between two large houses. On one side there was an old brown house. On the other side there was a large stone mansion. This was the home of old Mr Laurence and his grandson , Laurie. It was a very grand house and the rooms looked very comfortable behind the heavy silk curtains at the windows. But it was a house without life. The Marches’ house was different. It was always busy and full of noise and people.A few days after the party Jo saw Laurie again. He was standing at an upstairs window in the mansion and looking down at their garden. Beth and Amy were playing in 将混有少量高锰酸钾的氯酸钾放在试管中加热，直到不再产生气体为止，试管中固体剩余物共有A．2种B．3种C．4种D．5种