Difference between 'I am visiting' and 'I will visit'

[jorien]

Test No. errors/elem-4 "Present Tense", question 6

Later tonight I visit my uncle, who is ill in hospital.

(a) visit
(b) who
(c) is

Test No. errors/elem-4 "Present Tense", answer 6

Later tonight I am visiting my uncle, who is ill in hospital.

Correct entry: am visiting
The error was: (a) visit

You have found the error but your entry is incorrect.
Later tonight I will visit my uncle, who is ill in hospital.
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why is "will visit" impossible? what does it mean?

[Alan]

Will visit is too precise and means I am determined to visit but here you need the conversational expression I am visiting.
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English as a Second Language
You can read my ESL story Present Simple

[huyen]

I think I can use " I am going to visit" instead of " I am visiting" in this sentence. Do you agree?

[Mister Micawber]

.
Yes, that would work, too, Huyen.
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Native English teacher at Mister Micawber's