You can see many sentences like: "How you felt when you were in love", "How you can't sleep", "How you feeling" in friends series. My question is that are these sentences correct? They shouldn't be "How did you feel....", "How can't you sleep", "How are you feeling" ?
1 Answer
"How you feeling" is "How're you feeling" but the "'re" is very similar in sound to the "ow" of how and tends to be reduced in speech, to the point of being inaudible, and sometimes omitted when written.
The other phrases are not questions. They are noun phrases:
How I felt when I was in love was happy and dizzy.
You can form these noun phrases that start with How, What, Where etc. Phrases starting "How" mean "the way that (you felt when you were in love)"
These could also be errors, (for something like "how is it that you can't sleep") We couldn't decide if they are errors without some more context.