1. Only then did I understand the problem.
2. Only then I understood the problem.
(Which one is grammatical?)
3. Only after understanding the situation did he make a comment.
4. Only after understanding the situation he made a comment.
5. Only after understanding the situation, did he make a comment.
6. Only after understanding the situation, he made a comment.
(Which ones are grammatical?)
1 answer
#s 1, 3, and 5 are correct if you remove the comma in 5!