>>28
× "For dinner, I had a fried tuna"
◯ "For dinner, I had fried tuna"
With the indefinite article, "a fried tuna" means a whole tuna. Too much for one meal!

× "If I'm a college student, I wouldn't be able to..."
Present tense "I'm" does not match past tense "wouldn't".

◯ "If I was a college student, I wouldn't be able to..."
◯ "If I were a college student, I wouldn't be able to...

Use past indicative "I was", or use past subjunctive "I were". "I was" sounds certain, "I were" sounds more doubtful.