Re: Present perfect & past tense in the same sentence.
Glad to help. For my part, your question was not about how 'natural' the language of the sentence is. I wanted to address your query:
"The original question came up after various simple past and present tense statements were presented and then the question, Where is John? "
...and what information about this could be derived from the tense of the verb forms.
Mr.Matthews and I have different approaches when it comes to tutoring in English.
Re: Present perfect & past tense in the same sentence.
No native speaker of English says infelicitous stuff like that.
It is ambiguous and poorly constructed, so analysing it is pretty pointless really since one would just go round in circles searching for the intended meaning through a process of disambiguation.
Re: Present perfect & past tense in the same sentence.
Thanks Paul! That's what I thought (my gut instinct), but wanted to get confirmation. I've been speaking Polish for so long I forget my English grammar!