问题
选择题
下列关于原子结构的说法中，错误的是（）
A．核电荷数一定等于质子数
B．相对原子质量约等于质子数和中子数之和
C．质子数一定不等于中子数
D．一般来说，原子是由质子、中子、电子构成
答案
答案：C
题目分析：A、B、D说法正确；原子中质子数可能等于中子数，也可能不等于中子数。选C。
点评：原子中质子数和中子数未必都相同。
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下列关于原子结构的说法中，错误的是（）
A．核电荷数一定等于质子数
B．相对原子质量约等于质子数和中子数之和
C．质子数一定不等于中子数
D．一般来说，原子是由质子、中子、电子构成
答案：C
题目分析：A、B、D说法正确；原子中质子数可能等于中子数，也可能不等于中子数。选C。
点评：原子中质子数和中子数未必都相同。
Two friends visited the zoo together. The zoo was very large and it was 36 to go everywhere. They had to decide where and which animal to visit as their time was 37 . So both of them agreed not to 38 after choosing a 39 at every fork (岔路口). A road sign at the first fork 40 one way to the lion quarters and the other to the tiger hill. They decided on the 41 after a 42 discussion because lions were “the king of the grassland”. The second showed a division (路口) going separately to the panda and peacock. They 43 panda as it was the nation’s treasure and went its way. Thus they made choices all along the way and each choice meant 44 what they could regret. But they had to make it 45 , for it brooked (容忍) no delay. If they hesitated they would miss 46 . Only 47 decision could offer more chances for sightseeing and 48 possible regret. Life is 49 like this—choices often occur that one has to make, for example, between two 50 jobs, two fascinating wooers (追求者). To get one you 51 give up the other—you can get half of it. If you 52 weighing the pros and cons(权衡利弊) and calculating gains and losses, you will most likely 53 empty-handedness. Don’t be sad about it. 54 you have got half of the desirable things in life—something that is 55 to get.
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