I often Linda the old woman with housework last year.
A:see; helps
B:saw; helps
C:saw; helped
D:saw; help
在做光电效应的实验时,某金属被光照射发生了光电效应,实验测得光电子的最大初动能Ekm与入射光的频率ν的关系如图所示,由实验图象不可求出( )
下列洲界线中不属于亚欧分界线的是( )