CERTAINTY, POSSIBILITY, PROBABILITY, LIKELIHOOD
Predictions of the future vary insofar as the attitude of the speaker or the actual truth about facts related to the future vary. Predictions can have the following values: certainty, (im)possibility / probability, likelihood.
Usually expressed with the help of will + verb e.g. There will be a crisis next year, too. It’s in the newspapers! The shareholders won’t be very happy; the dividends have lost their value on the market.
Usually expressed by modals like may / might (not) + verb e.g. There may be a crisis next year, too – nobody can tell for sure. They might have to move; at least, that’s how the rumours go.
Situations that are likely to happen can be expressed using the modal could + verb or may / might + verb e.g. There could be a problem in the fact that the suppliers haven’t been paid on time.
WILL + VERBBE GOING TO + VERB WILL + VERB IS USED TO MAKE A PREDICTION WE ARE CERTAIN OF, USUALLY IN A FORMAL CONTEXT e.g. In ten years’ time, people’s lives won’t (will not) be different. WILL + VERB IS USED WHEN PERSONAL OPINIONS ABOUT A FUTURE ACTION ARE EXPRESSED (USUALLY WITH THE HELP OF CERTAIN EXPRESSIONS, SUCH AS: I THINK THAT, I’M SURE, I BELIEVE THAT, PROBABLY, DEFINITELY…. e.g. I’m sure it will rain tomorrow. BE GOING TO + VERB IS USED TO MAKE A PREDICTION WE ARE CERTAIN OF, IN A MORE INFORMAL CONTEXT e.g. Yuck! It’s going to be hot tomorrow. BE GOING TO + VERB IS USED WHEN EXPRESSING PREDICTIONS BASED ON A CERTAIN PROOF OR EXPECTANCY e.g. Look at the sky! It’s going to rain!
WILL + VERBBE GOING TO + VERB On-the-spot decisions about the future e.g. Hmmm! I like this jacket! I will take it! Promises of actions for the future e.g. Don’t worry! I promise I will pay you back! Already taken decisions e.g. I have to write an essay for the next week. I’m going to stay home tonight.