is to visit / is visit

English as a Second Language English Vocabulary, Grammar and Idioms
1
  1. All I want is to visit England.
    1a. All I want is visit England.
  2. What I want is visit England.
    2a. What I want is to visit England.
  3. The best thing is visit England.
    3a. The best thing is to visit England.
  4. All I want to do is to visit England.
    4a. All I want to do is visit England.
  5. What I want to do is to visit England.
    5a. What I want to do is visit England.
  6. The best thing to do is visit England.
    6a. The best thing to do is to visit England.
    Please correct and comment.
    Thanks.
2

Incorrect
1a 2 3