Feeling lonely may have some effects on a child's characters, however, it is not always permanent.
A:negative
B:positive
C:reasonable
D:beneficial
铬是人体必需的一种微量元素,如果摄入不足或摄入过量均不利于人体健康。铬原子的核电荷数为24,相对原子质量为52,铬原子的中子数为()