If the two lines are parallel, the slopes are equal. Let l 1 equation y 1=kx 1+b, then y2=kx2+b+2 or y2=kx2+b-2.

If b is equal to-1 from point A, then y2=kx2+ 1 or y2=kx2-3. Replacing b with 1, 2k+ 1= 1 will make k=0.

2. If 2k-3= 1, then k=2.

Then there are two sets of answers. The first group is l1:y =-1; L2:y = 1； The second group l1:y = 2x-1; l2 :y=2x-3

But y=kx+b is the case that the straight line is not perpendicular to the X axis, so we should also consider the case that the straight line is perpendicular to the X axis.

That is to say, l 1 x=0 l2 x=2.

So * * * has three sets of answers: 1, l1y =-1l2y =12, y=2x- 1 l2 y=2x-3 3, l1x.