They have demonstrated the value of postcognition.
A struggle is an effort to do something that is very difficult for you to do.A struggle is a battle, or difficult effort, against someone or something. It can be a conflict with a person, or an effort to overcome some obstacle, debility, or disease.
The opposite would be strenuous (requiring effort), or difficult.
difficult, challenging
The word "difficult" is an adjective. It is used to describe nouns by indicating that something is not easy or requires effort.
extreme cold weather
Put forth your best effort no matter what
Curfews have nothing to do with solving crimes. Curfews are imposed in an effort to reduce crime, to keep children safe, and to reduce overall disorderly activity committed by (primarily) the age group that is targeted. (Whether or not it is effective is often in debate.)They have nothing to do with investigation into crimes that have already been committed.
To the best of my knowledge - and I have made some effort to investigate the matter - the profession of psychic is fundamentally fraudulent, and there are no honest psychics. Psychics can be nice people, who aspire to be possibly entertaining, or even psychologically therapeutic for the people who hire them, but they do not have real psychic powers. It's too bad, because we could really use some real psychics. For example, they could tell us where Osama bin Laden is hiding.
The answer depends on your aptitude, the amount of effort that you are prepared to put in and the quality of your teachers.
D. Put forth your best effort no matter what. :D
Learning statistics is more or less difficult depending upon your aptitude for the subject and on how much effort you are prepared to put into learning it.
The doctor spared no effort in trying to save the patient's life.