writes:

I see you've had little experience with foreign born technical
people.

I teach them English, so I have years of experience with them.

If they are young enough, their English spelling and grammar may
become "fluent", but not likely withoug formal instruction and
very unlikely if their native language is very different from
English as in Chinese or Farsi.

They need not be young, and I know people who have become completely bilingual
in adulthood. It's mostly a matter of motivation, and practice.

Their conversational English will be OK, but their written English
will be full of strange grammatical constructions and word use.

Not if they are smart and motivated.

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