This is my code:

```
Show[{ParametricPlot3D[{x, y, 0}, {x, -4, 4}, {y, -4, 4}, 
   PlotStyle -> LightGray, Mesh -> None],
   ParametricPlot3D[{0, 0, t}, {t, -8, 8}, PlotStyle -> Blue],
   ParametricPlot3D[{x, 0, z}, {x, -3, 3}, {z, -3, 3}, Mesh -> None]}]

```

Output [![out put ](https://i.stack.imgur.com/8dOSA.png)](https://i.stack.imgur.com/8dOSA.png)

I noticed that the intersection point of the vertical line with the horizontal plane is not on the intersection line of the two planes, although the vertical line is defined on the vertical plane. By setting the axes of the Plot at the origin, I found that the intersection line of two planes is displayed correctly. 

So my questions why the insection point of the vertical line with the horizontal plane is not displayed right? How can I make it right? Thanks a lot!