The Future Tense
Be going to and will are often used to talk about something that we are going to do in the future.
a.) I am going to leave at 6 p.m. tomorrow night.
b.) I will leave at 6 p.m. tomorrow night.
c.) Linda is going to go to the party Saturday.
d.) Linda will go to the party Saturday.
In the examples above, sentences (a) and (b) have the same meaning and sentences (c) and (d) have the same meaning. Notice also that in sentence (c) and (d) that the verb go is used in the infinitive go to. In the other examples the simple present tense verb follows be going to and will.
In the examples above, it is 100% certain that the events described will happen at the time stated. In other words, when a person uses be going to or will they are sure that they will do what they have planned. But what if the person speaking isn't sure? What if there is only a possibility that an event will happen? In that case, you can use the word probably to let the person you're talking know that you aren't sure whether you will do something or not.
a.) Mary will probably go out tonight.
b.) Mike will probably not visit this weekend.
c.) Mike probably won't visit this weekend.
When used in a positive statement, probably comes between will and the main verb as in sentence a.) above. In a negative sentence, probably comes between will and not in formal speech, as in sentence b.), or in front of won't in informal speech as in sentence c.) above. Please note that probably is not used with be going to.
When you use probably with will you are actually expressing possibility. Other words that can be used to state possibility are may, might and maybe. May, might and maybe, when used to express possibility all have the same meaning.
a.) It may rain tomorrow.
b.) It might rain tomorrow.
c.) Maybe it will rain tomorrow.
All three sentences have the same meaning, note however, the sentence construction. In sentences a.) and b.) the words may and might come after the subject. In sentence c.) maybe comes before the subject.
Note: Many students confuse maybe with may be. Maybe is an adverb meaning perhaps, comes before the subject, and is spelled as one word. May be is a verb phrase, comes after the subject, and is spelled as to words. Compare the following sentences.
a.) Jim might be sick
b.) Maybe Jim is sick.
c.) Jim may be sick.
Using the Present Progressive to Express Future Time
Future time is often expressed using the present progressive instead of will or be going to.
Verbs such as come, go, stay, arrive, leave are frequently used in the present progressive to express future time. Such verbs express definite plans.
Verbs expressing planned means of transportation in the future are also frequently used in the present progressive; for example, fly, walk, ride, drive, take (a bus, a taxi, etc.).
Sentences a.), b.) and c.) all have the same meaning.
a.) Marty will come to the party tomorrow night.
b.) Marty is going to come to the party tomorrow night.
c.) Marty is coming to the party tomorrow night.
Sentences d.), e.), and f.) all have the same meaning.
d.) Mike and I will go to a movie tonight.
d.) Mike and I are going to go to a movie tonight.
f.) Mike and I are going to a movie tonight.
Sentences g.), h.), and i.) all have the same meaning.
g.) I will fly to Chicago next week.
h.) I'm going to fly to Chicago next week.
i.) I'm flying to Chicago next week.
Sometimes a speaker will use the present progressive when he or she wants to make a very strong statement about a future activity, as in the dialog below.
A: You shouldn't buy that used car. It's in terrible condition. It costs too much. You don't have enough money. You'll have to get insurance, and you can't afford the insurance. Buying that used car is a crazy idea.
B: I am buying that used car tomorrow morning! My mind is made up. Nobody-not you, not my mother, not my father-can stop me. I'm buying that car, and that's it! I don't want to talk about it anymore.
A: Oh well, it's your money.