题目

请听材料，回答所给问题 （1） What did the speaker do yesterday morning? A . He went fishing. B . He went hiking. C . He went horse-riding. （2） When do the campers help with cooking? A . In the morning. B . In the afternoon. C . In the evening. （3） What was the speaker in charge of yesterday? A . Preparing the hotdogs. B . Making the campfire. C . Looking for sticks. （4） How long does the summer camp last? A . Eight days. B . Seven days. C . Six days.如图所示装置可用于测定空气中氧气的含量，实验前在集气瓶内加入少量水，并做上记号．下列说法中不正确的是（ ）A．该实验证明空气中氧气的含量约占B．实验时红磷一定要过量C．实验前一定要检验装置的气密性D．红磷燃烧产生大量的白烟，火焰熄灭后立刻打开弹簧夹