I sometimes have some pb with these 2 tenses too. I don't think they're always interchangeable though.
"In exactly two days I will be sunbathing on the beach" (I'll be doing it at that time => progressive aspect)
"In two days I will set off to Hawaii" (no progressive aspect)
Well, I agree with the book. We could rephrase it: "he did his homework while watching TV" (sounds even more natural to me).'Watching TV, he did his homework' should mean that the person did them at the same time, according to a grammer book I read recently. If the book's explanation might be correct, the above sentences should be incorrect that they can interchangeable
Could you please help me get out of this confusion?
Correct. First he watched TV, then he did his homework. Two consecutive actions.'Having watched TV, he did his homework' should mean that the person did that watching TV, then he started to do his homework. That is in my book correct. What about yours?