travel と trip の違い｜a travel はなぜ間違い？

I will give you some English sentences I wrote.
Check only one point:
Are the nouns "travel", "trip" and "journey" used correctly?
(Use these rules:
- travel (noun) = the activity of travelling in general. It is uncountable. Example: Air travel has become much cheaper.
- trip = one time you go somewhere and come back again. It is countable. Example: I met him on a recent trip to London.
- journey = the time you spend travelling from one place to another, especially in a vehicle. Example: The journey from the airport takes about 20 minutes.
- Do not say "a travel" for one trip. Do not mark "travel" as wrong when it is a verb (I travel to work by train.).)
Do NOT change anything else.
Do NOT correct a sentence that is already right.

For each sentence, answer in this form:
番号:
元の文: (my sentence)
直した文: (the corrected sentence, or "OK" if nothing needs fixing)
理由: (one line of Japanese)

Use simple Japanese in the reasons.

My sentences (the Japanese meaning is in brackets):
"""
（ここに、自分で書いた英文を5つ貼る。日本語の意味も括弧で添える）
"""

Let's practice a short conversation.
You are my friend. I just came back from a trip.
Ask me one question at a time about my trip: where I went, how I got there, and what I did.
Wait for my answer before you ask the next question.

After each of my answers, check only the nouns "travel", "trip" and "journey":
- travel (noun) = the activity of travelling in general. It is uncountable. Example: Air travel has become much cheaper.
- trip = one time you go somewhere and come back again. It is countable. Example: I met him on a recent trip to London.
- journey = the time you spend travelling from one place to another, especially in a vehicle. Example: The journey from the airport takes about 20 minutes.
- Do not say "a travel" for one trip. Do not mark "travel" as wrong when it is a verb (I travel to work by train.).
If I made a mistake, show it in this form:
直し: (the corrected sentence)
理由: (one line of Japanese)
If there is no mistake, just say "Good!" and ask the next question.

Do NOT correct other mistakes.
Do NOT ask more than five questions.
Use easy English in your questions.

Give me a 4-choice quiz on the nouns "travel", "trip" and "journey".
Make 5 questions.
Show only ONE question at a time.
Do NOT show the answer until I reply.

Use these rules:
- travel (noun) = the activity of travelling in general. It is uncountable. Example: Air travel has become much cheaper.
- trip = one time you go somewhere and come back again. It is countable. Example: I met him on a recent trip to London.
- journey = the time you spend travelling from one place to another, especially in a vehicle. Example: The journey from the airport takes about 20 minutes.
- Do not say "a travel" for one trip. Do not mark "travel" as wrong when it is a verb (I travel to work by train.).

Use this form for each question:
Q(number): (an English sentence with a blank ___ )
(A) (B) (C) (D)

After I answer, tell me:
正解: (the letter)
理由: (one line of Japanese)
Then show the next question.