1. He caught a big fish, but he put it back.
2. He caught a big fish, but he turn it back.
3. He caught a big fish, but he returned it.
4. He caught a big fish, but he returned it back.
5. He caught a big fish, but he released it.
6. He caught a big fish, but he released it back.
[Can we use all the expressions? Are they all the same in meaning? Which expressions are not acceptable?
#5 is the only correct expression.
#s 1 and 3 are close, but not quite right.
All the others are incorrect.
All the expressions you provided convey the same meaning, which is that the person caught a big fish and then released it. However, some of the expressions are more commonly used and more grammatically correct than others.
Expressions 1, 3, 5, and 6 are all acceptable and commonly used:
1. He caught a big fish, but he put it back.
3. He caught a big fish, but he returned it.
5. He caught a big fish, but he released it.
6. He caught a big fish, but he released it back.
These expressions use the verbs "put back," "returned," or "released" to indicate that the fish was let go or returned to its natural habitat.
On the other hand, expressions 2 and 4 are less commonly used and not grammatically correct:
2. He caught a big fish, but he turn it back.
4. He caught a big fish, but he returned it back.
In expression 2, the verb "turn" should be replaced with "put back" or "released." In expression 4, the phrase "back" should be omitted since "returned" already implies that something is being taken or sent back.
In summary, expressions 1, 3, 5, and 6 are acceptable and commonly used to convey the meaning of catching a big fish and releasing it. Expressions 2 and 4 are not acceptable due to grammar issues.