【简答题】CI起源于 () ,系统集成于(),20世纪80年代末期引入()。
【简答题】First Lady Michelle Obama is a big fan of volunteering. Volunteering means working for free to help someone else. Mrs. Obama says volunteering is very important. “It should be part of everyone’s life,...
【单选题】分子间同时存在引力和斥力,当分子间距增大时,分子间( )
【简答题】Amanda is a very kind girl. She is 1 willing to help people who are in trouble. Now Amanda is 2 in the University of Texas. At the same 3 , she is volunteering to teach at Heart House in her free t...
【多选题】关于分子间相互作用力的以下说法不正确的是
A.
分子间同时存在着引力和斥力,分子间斥力实质为电荷之间的库仑力,分子间引力实质为万有引力
B.
当分子间距离 r = r 0 时,分子间的分子力为零,此时分子间没有相互作用力
C.
当 r < r 0 时, r 增大,分子间斥力、引力都增大,但斥力增加更快,故分子间作用力体现为斥力
D.
当 r > r 0 时, r 增大,分子间引力减小,斥力也减小,但斥力比引力减小得更快,故分子间作用力表现为引力,且分子力随着分子间距 r 的增大而先增大后减小直到为零