Q: Valid English sentence (grammatically) or not: They can't do it, can they?
OPTIONS:
- unacceptable
- acceptable

A: acceptable

Q: Valid English sentence (grammatically) or not: I assumed him to be innocent
OPTIONS:
- unacceptable
- acceptable

A: acceptable

Q: Valid English sentence (grammatically) or not: What it is certain that he was wearing is this hat.
OPTIONS:
- unacceptable
- acceptable

A:
acceptable