I've just started learning German and one of the books I was reading explains that you can use various words like articles by using the endings of the article cases. My book just says:
this/these dies- (close to speaker) that/those jen- (away from speaker)* all all- (singular or plural) each, every jed- (always singular) which welch- some manch- (almost always plural) such solch- *Jener used relatively rarely in German, and instead of it one can use dieser (this/that, these/those)
Some of the restrictions of plurality make sense to me: jed- is always going to be singular because it is referring to the individuals e.g. jeder Baum means "every tree", but some of the others confuse me, namely all- and manch-.
I would have expected all- and manch- to always be plural because they are used to talk about many of something e.g. alle Bäume means "all trees". When are the singulars used?