Quite often my written answer is marked wrong simply because I failed to insert a space before punctuation. I am trying to train myself to add the space, but it does not come naturally for me when I write in English. Why do you insert a space before certain punctuation marks, notably exclamation, colon and question mark? For example: This sentence ! and This list : and This question ?
It seems you do not insert a space before other punctuation marks, such as period or comma, for example:
Like this, or Like that.
Why ?