Charlie studied Chemistry in a famous college for four years. He studied hard and did well in all his subjects. He hoped to become a good teacher. This year he left the college and began to work in a middle school. He likes his students and wants them to get good marks so he does his best to make his classes lively and interesting.
One day he carefully explained a chemical reaction(反应)to the students of Grade 2 in the chemistry lab.
“Be careful. Everyone,” he said loudly. “Before I make the experiment, there’re twenty five atoms of carbon（碳原子), but after I finish it, there’re twenty four atoms of carbon left!”
He stopped to watch the classroom and hoped his students would go on explaining it. But the young men looked at each other and nobody answered him. He had to ask, “What happens? What makes the atom disappear? ”
The classroom was very quiet and none of the students looked at their teacher.
“Who can tell us where it has gone?”
Suddenly a soft voice came from the back row, “We did not see anybody leave the lab!”
60.Charlie began to work in the middle school because _______.
A. he had been in the school for four years 
B. he couldn’t do anything except teaching
C. he hoped to become a good teacher        
D. he did well in all his subject
61. Charlie hoped ____,so he does his best to make his classes lively and interesting.
A .all his students could understand him                    
B .his students wouldn’t be afraid of him
C. his students carefully watched him doing the experiment
D. his students would do well in chemistry.
62. That day Charlie wished ____.
A. his students could learn the chemical reaction
B. his students should find the atom of carbon
C. his students could count(数) the atoms of carbon
D. his students could make the experiment
63. The students couldn’t answer Charlie’s questions because ____.
A. none of them had seen the atoms                         
B. they were afraid of the teacher
C. the chemical reaction was too complicated            
D. they all wanted to drop the subject