All people will ________sadness and happiness in life.
A:go through
B:go across
C:look through
D:come across
若夫日出而林霏开,____,晦明变化者,____。(欧阳修《醉翁亭记》)
已知向量a=x+z,3,b=2,y-z,且a⊥b.若x,y满足不等式x+y≤1,则z的取值范围为( )