题目

 Dear Sir or Madam,    Last Thursday, I traveled on the 8:00 a.m. train from Glasgow to London King’s Cross and I was quite angry about the service of your station.      The train didn’t come on time and it was forty minutes late when it left Glasgow. A man at the station said sorry to us, but he didn’t give us any reasons for the delay (误点). We then had further delays on the way and had to wait another thirty minutes. So I missed my plane from London to Frankfurt and had to wait for several hours.      What’s more (更重要的是), the service on the train was某实验室将水稻幼苗固定于无底反应瓶中，实验装置如图所示。该装置是根据比重浮沉的原理，由称量浸没在液体中的瓶所受浮力的改变值测量气体量的改变。I.利用该装置可以测定呼吸作用与光合作用导致的瓶内气体容积的变化。调节天平平衡，在适宜的光照强度下，光照15 min后，指针向          （左、右）偏转，原因是       。接着进行遮光处理，指针将      ，原因是      。Ⅱ．利用该装置还可以探究水稻幼苗地上部分能否向根系供氧，以天平指针偏转1格所需要的时间作为观测指标，完成实验。（1）步骤：步骤1：将装置中的缓冲液换成      溶液；步骤2：调节天平平衡，                        ，记录天平指针偏转l格所需要的时间记为。步骤3：        ，记录天平指针偏转1格所需要的时间记为。（2）预期实验结果并得出结论：