When is it?
It's important to show your work on those problems, so get in the habit of writing it all out like, "The words of purchase 'to A' denote A as the grantee of the estate. The words of limitation 'for life' denote a life estate. There are no other words of limitation in the conveyance, therefore A takes possession."
Then do the same with the future interests and the rest.
Take one interest at a time, working from left to right with no skipping around, and you should be good.
And have fun with the rule against perpetuities! I find drawing a timeline helps with those.