题目

If you’re a male and you’re reading this, congratulations: you’re a survivor. According to statistics, you are more than twice as likely to die of skin cancer as a woman, and nine times more likely to die of AIDS. Assuming you make it to the end of your natural term, about 78 years for men in Australia, you’ll die on average five years before a woman. There are many reasons for this — typically, men take more risks than women and are more likely to drink and smoke — but perhaps more importantly, men don’t go to the doctor. “Men aren’t seeing doctors as often as they三个原子核X、Y、Z，X核放出一个正电子后变为Y核，Y核与质子发生核反应后生成Z核并放出一个氦核，则下面说法正确的是 A. X核比Z核多一个质子                               B. X核比Z核少一个中子 C．X核与Z核的总电荷是Y核电荷的3倍     D. X核的质量数比Z核质量数大3