I’ve come across this quite a lot recently. Research and knowledge, study and information… are they count or non-count?

Research: non-count. (It’s a noun, verb, and adjective.)

I need to do more research before I can create my giant robot.

Information: non-count.

I don’t have a lot of information. Do you know an expert we could ask?

Knowledge: non-count

James has a lot of knowledge about writing.

Study: count. (Here we’re using it as a noun, but it is also a verb.)

The scientists carried out three studies before they wrote their paper.

Fact: count.

This is a fact: Canada’s really big.

Opinion: count.

My friend and I have two very different opinions about that subject.