如图所示,一带电量为q的金属球,固定在绝缘的支架上,这时球外P点的电场强度为E0 , 当把一电量也是q的点电荷放在P点时,测得点电荷受到的静电力为f;当把一电量为aq的点电荷放在P点时,测得作用于这点电荷的静电力为F , 则在国际单位制中() A . f的数值等于qE0 B . F的数值等于af C . a比1小得越多,F的数值越接近af D . a比1小得越多,F的数值越接近aqE0In the study of modern science, there are
many cases _____ soldiers can teach officers.
A.when
B.who
C.which
D.where