题目

根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。 There is an English saying:“.” Until recently, few people took the saying seriously. Now, however, doctors have begun to look into laughter and the effects it has on the human body. . Tests were carried out to study the effects of laughter on the body. People watched funny films while doctors checked their hearts, blood pressure, breathing and muscles. It was found that laughter has similar effects to physical exercise. . If laughter exercises the body, it must be ben根据玻尔理论，氢原子的能级公式为（n为能级，A为基态能量），一个氢原子从n=4的能级向低能级跃迁，则下列分析正确的是A. 该氢原子最多可以辐射3种不同频率的光子B. 该氮原子一定可以辐射6种不同频率的光子C. 该氢原子可能辐射的光子中频率最大的光子能量为D. 该氢原子可能辐射的光子中频率最大的光子能量为