Don't know if this is actually considered a shortcut, but if you look at the
menu bar, you'll see that *every* menu selection has a letter underlined.
This means that the particular menu can be accessed by holding the <Alt> key
and typing the underlined letter.
ALSO, most of the submenus have the same feature.
SO ... for "PrintPreview", just use,
<ALT> <F> <V>
I'm not aware of one for "left align".
But following the above conditions,
<ALT> <O> <E>, will take you to the cell alignment window, where you can
adjust to "left", but I'm sure a click on the toolbar icon would be much
easier and quicker, even if you have to leave the keyboard and grab the
mouse.