The word up can be used as a preposition or as an adverb particle. For example, it is an adverb particle in the expressions stand up and blow up. Note that an adverb particle doesn’t have an object. A preposition is always followed by a noun or a noun equivalent which serves as its object.
- John is already up. (= John is out of bed.)
As a preposition up is used to talk about position in or movement to a higher or more important place or degree etc.
- Pull your socks up.
- He is going up to London. (= He is going from the country to London.)
When you are up to something, you are occupied or busy with it.
- What’s he up to?
- He’s up to no good. (= He is doing something wrong.)
Up to can also mean equal to.
Not up to much = not very good
- I don’t feel up to doing much. (= I don’t feel well enough to do much.)
What’s up? is the slang for What’s the matter?
The game’s up, it’s all up. (= We are beaten, we have lost.)
Ups and downs = changes of fortune.
- I have had my share of ups and downs, but life has generally been good to me.