已知x=2,y=﹣3是二元一次方程5x+my+2=0的解,则m的值为( )
A:4
B:-4
C:83
D:-83
Who has Mr Black had ____ (design) for his new house?
造成一天中气温变化的最主要的原因是( )
极昼和极夜现象与____、____和____有关。