短文填空
The lecture on (1)__________(smoke) was over at last. While we boys (2)__________(rush)
towards the playground, Jim passed by the table. The watch, which Mrs. Smith had laid on the table
when she started her lecture, disappeared. We were going back for class again when the headmaster
(3)__________(call) us together and said, "I've got a little job for you boys. Mrs. Smith has just lost
her watch on the playground.
This kind of thing (4)__________(happen) before." He said," It just fell off her wrist(手腕). So, look
around for it, will you? (5)__________(see) ff you're clever enough for it. You (6)__________(get) a
useful reward."
At once we started looking for the watch. Everybody wished to be the lucky one. Suddenly, Jim
(7)__________(stop) and bent(弯) down as if to pick up something. And the next moment he was in
front of Mrs. Smith, all smile, turning in the watch to her. Mrs. Smith, however, (8)__________(not be)
pleased at all. In fact, she looked angry. She took the watch without even a "Thank you. "
Jim got his reward ---a large piece of paper from the headmaster. He told Jim (9)__________(write) a
composition on the danger of smoking. What (10)__________(can) poor boy Jim write about? He hadn't
listen to the lecture and had nothing to say on the lecture.
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/Mn2+，电极反应有H+参加；由于酸碱反应，酸度会影响
、IO-的浓度，故这些电极的电极电势均受酸度影响。Na+/Na电对，电极反应无H+参加，酸度的改变不影响氧化态、还原态的浓度，所以该电对电极电势不受酸度变化的影响，故答案D正确。