&lt;Shift&gt; + i   Mark as read    -Marks your message as 'read' and skip to the next message.

&lt;Shift&gt; + u   Mark as unread  -Marks your message as 'unread' so you can go back to it later.

Full list of Keyboard shortcuts

What is the keyboard shortcut for 'Mark as read' in GMail?
So, say we are working with non-CH mathematics. This means, AFAIK, that there is at least one set $S$ in our non-CH mathematics, whose cardinality is intermediate between $|\mathbb{N}|$ (card. of naturals) and $|\mathbb{R}|=2^\mathbb{N}$, the continuum.

Question: what kind of objects would we find in this set $S$?

Also: is this mathematics radically different from the one where CH holds?

Specifically, are there results that are used in everyday math , at a relatively introductory level, which do not hold on our non-CH math.?. What results that we find in everyday math would not hold in our new math?  Would there, e.g., still exist non-measurable sets? Maybe more specifically: what results depend on the CH?
