This is a test of commonsense. Complete the next sentence:

How to be familiar with various types of mechanisms of organic reactions
Organic reactions can usually proceed in one of two ways.
One of them is concerted reaction that takes place in one step with one transition state. The other type of reactions in organic chemistry is the non-concerted type of reactions.
The latter type is the dominant type of most chemical reactions. Non-concerted organic reactions usually have intermediate structures that are highly reactive carbon species.