Expression ** If ( true do this, false do nothing just let it through)

[Moniker]

1. Form VIew
2. Column Type "Text"
3. Want to write the expression for the followings,

The part needed to solve is bold & underlined. (thank you all in advance)

if( [This column] = " Value", "if true" list(a , b), "if false" I want this expression to do nothing so that I can write.

[Steve]

You'll need two columns, one for the limited options and one for the free-form entry. Then use Show? or Editable? to hide or show the appropriate one.

[Moniker]

lol, Thank you Steve. 
I have too many columns to manage so I was hoping for "Skip this expression when its false" type expression. Because with that column count would be significantly reduce. 
But it seem that there isn't one.
And again, Thank you so much for the quick response and your time.