The second to the fourth all work, The first does not.
And the word is "grammatically". "That" should not be capitalized in the second.
Student or Learner
I have a question.
"A pen what you used"
"A pen That you used"
"A pen which you used"
"A pen you used"
Which one is the best?(grammartically)
Thank you for your answer.
And The second to the fourth all work but they are all the same things?