My bike is broken. Could you help me to _________?
A:fix it up
B:set it up
C:make it up
D:put it up
选文中有一句话暗示了小说的社会背景,是哪一句话?
如图,在矩形ABCD中,AB=4,BC=5,点E、F、G、H分别在已知矩形的四条边上,且四边形EFGH也是矩形,GF=2EF.若设AE=a,AF=b,则a与b满足的关系为( )