Q: Valid English sentence (grammatically) or not: I think that learning English is not all that easy.

A: acceptable

Q: Valid English sentence (grammatically) or not: The contestant who won the first prize, who is the judge's brother-in-law, sang dreadfully.

A: acceptable

Q: Valid English sentence (grammatically) or not: The vase got broken that Sheila had brought all the way from.

A:
acceptable