Question e-mailed to me by FH, an English teacher in Iran (June 16, 2013):
“What is the difference between the following sentences?
“(A) ‘I will study in the library tomorrow.’
“(B) ‘I am going to study in the library tomorrow.’”
My reply to FH:
The two sentences above are using two different forms of the simple future tense in English. The first uses the modal “will” together with the verb “study” to express the idea that the speaker will do that activity; it’s a simple expression of futurity. The second uses the so-called “be going to + verb” form of the future tense. This form has practically the same sense of futurity as the “will + verb” form, but it adds the element of an intention or plan to do the activity.
While practically interchangeable in the context of the two sentences presented above, these two future-tense forms could have significantly different meanings or nuances in other contexts.
Generally, the “will + verb” form is used to convey the willingness to do something on one’s own volition, as in “I will sleep early tonight,” or in response to somebody’s request, as in “I will come tomorrow as you wish.” The “will + verb” form is also used to express a promise, as in “I will meet you at the airport on Tuesday.”
On the other hand, the “be going to + verb” form is used to signify an intention, expectation, or plan to do something, regardless of whether the action or activity has been clearly figured out or is just a wish or conjecture. Clearly figured-out future action: “We are going to tour Europe on our honeymoon.” “Based on the first-month gate receipts, this new horror movie is going to break all box-office records.” Wish or conjecture: “I am going to be a successful doctor someday.” “We are going to be mortal enemies at the rate we are fighting.”
When used to express the idea of a general prediction or guess about the future, the forms “will + verb” and “be going to + verb” can be used interchangeably to mean precisely the same thing. Compare: “This rainy season will be a perilous time for low-lying areas.” “This rainy season is going to be a perilous time for low-lying areas.” In situations like this, the speaker has little or no control at all on what might happen.
