Capillary action is bad if you want to keep two liquids separate. Capillary action is difficult to control in terms of flow rate.

An action recipe has the directions written in with the ingredients. It's usually in paragraph form and can make figuring out the ingredient difficult.

It would prove a little difficult to bring an action.

Look for the word that describes the action. Sometimes it may be difficult, but it is there.

This is the compulsive repetition of a simple action ovear again and is difficult to stop