Which sentences is correct ?
I will be healthy when I ....... older

1. Will be
2. Would am
3. Be
4. Am

Thanks

Question

Which sentences is correct ?
I will be healthy when I ....... older

1. Will be 
2. Would am
3. Be
4. Am

Thanks

Answer

After "when," the simple present is used to express future time.  So, the answer is 4.

More information here:
https://www.ef.com/ca/english-resources/english-grammar/simple-present-tense/
[excerpt]
To express future time, after some conjunctions: after, when, before, as soon as, until:
He'll give it to you when you come next Saturday.

Answer

Definitely "am" is correct here. The "when I..." forces the present tense, though I can't say exactly why.
Examples:
"When he is older he will be tall"
"When she is angry her ears get red"
"When you are older you'll understand"

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