How about this one so confused !!

29.DS  在数轴上,x在y,z的左边，问xyz在不在x的左边

1）xy<0

2) xz<0

答案是E

x在y,z的左 
so x<y and x<z 

(1)xy<0  x=-    y=+

(2)xz<0  x=-    z=+                                              xyz               x          0       1        2

so   x>xyz                           _________________|_________|_____|____|_____|____________