posted by John .
1. He is using the computer.
2. He is working on the computer.
3. He is working at the computer.
(Which one is correct? What is the corrct preposition?)
4. The round trip air fare is one of the cheapest one.
5. The one way ticket to the country is very expensive.
6. The plane will be convenient because I have to pay expensive air fare.
7. The Korean Air Line is not so expensive, but, anyway, we have to pay about 800,000 won for round trip air fare.
(Would you check the english expressions, please?>)
1-3 - All are correct.
4 - OK except for the last word -- should be "ones."
5 - the word "one-way" needs a hyphen
6 - OK
7 - Remove "The" before "Korean" and the comma after "but" - everything else is fine.
In #1, if he is using the computer, he is "typing" so to speak. If he is working on the computer he may be doing the same thing OR he is fixing some part of the computer.
4. "one" of implies the noun must be plural = one of the cheapest ones. And "round-trip" is hyphenated when used as an adjective.
5. also "one-way " modifying the noun "ticket."