Putting a spoiler on MathJax equations does not work well sometimes, as reported [here][1] (1st answer).

For example,

> $$a=1$$ $$b=2$$ $$c=3$$

can be written using

    > $$a=1$$
    > $$b=2$$
    > $$c=3$$

or

    > $$a=1$$ $$b=2$$ $$c=3$$

**However**, writing

    >! $$a=1$$ $$b=2$$ $$c=3$$

or

    >! $$a=1$$
    >! $$b=2$$
    >! $$c=3$$

results in no line breaks in the preview pane. To see this in action, edit this post and look at this block:

>! $$a=1$$
>! $$b=2$$
>! $$c=3$$

**Where have the line breaks gone?**


  [1]: http://puzzling.stackexchange.com/questions/14743/ages-of-a-and-b-self-reference-in-past