Pick the correct option?

My sister studies hard I think she (will)/(is going to) come in first.
My brother is playing really well I think he (will)/(is going to) win.

1 Answer

My sister...will...
My brother...is going to...

Explanation:

We have a couple of things going on here (and a correction that should be mentioned for the question itself).

  • The first is the difference between simple tenses and continuous (also known as progressive) tenses.

In the first sentence, we're told "My sister studies hard." This is a simple tense (present tense to be specific). What we're being told is that the sister studies hard. We don't know if she's currently studying.

In the second sentence, we're told "My brother is playing really well". This is a progressive tense (also present progressive). What we're being told is that the brother is playing a game at this moment and that he's playing well.

  • The second is the rule, in English, to mirror tenses. Basically, if you are using a tense in one part of the sentence, you want things to line up so that they make sense. It's very much like what we do when we say something like "They are" and not "They is" - there needs to be agreement between noun and verb.

And so in our first sentence, we start with present simple tense. Since the test is somewhere in the future (it isn't occurring now), we use the simple future tense to indicate that when the test occurs, she will come in first. Choice 1 - Will.

In the second sentence, we have a game that is actively happening. The result of that game is being determined by the play now. And so we use the future progressive tense to indicate that we know that the end of the game is coming up and that he will win because he's playing well. Choice 2 - Is Going To.

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Now to a correction in the question. There should be periods between the two clauses in each question:

My sister studies hard . I think she will come first.
My brother is playing really well . I think he is going to win.

And what was probably an oversight, but the second option in first question should probably have been "is going to".