3650220/ You should telephone and also write, just to be sure.
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https://forum.wordreference.com/threads/as-well-as.3650220/
You should telephone and also write, just to be sure.
I think there are two possibilities for idiomatic "as well as": either it's a compound coordinator or it's an adjunct where the second "as" is a preposition.
I'd be inclined to say that in your particular example "as well as" behaves like the coordinator "and", and thus the former analysis is the correct one.