It's kind_________ you to help organize our Helping Hands Meeting because it's still difficult _________ the children in poor areas to go to school.
A:for; of
B:for; for
C:of; of
D:of; for
过圆上一点可以作圆的最长弦有( )条.
下列建设项目不属于“一五”期间完成的是( )
我国的地势特点对河流产生的有利影响是( )