I was taught that both present participle(doing something) and prepositional phrase (by doing something) can act as adverbial modifies the verb in the main clause, and can indicate in what(which) way or method something was done or achieve. Does it mean that they are interchangeable in this kind of situation?
1) You can avoid a lot of problems giving in to her, and you can also cause a lot of problems giving in to her.
2) You can avoid a lot of problems by giving in to her, and you can also cause a lot of problems by giving in to her.
Is there any differences between 1) and 2)？
How will you understand the first sentence when you see it?
How to decided when we need the word by to make present participle ?
My understanding is if the meaning still clearly expressed after the word by was dropped. Then we can left it out, but if the meaning of the sentence will be ambiguous, and then we have to keep the word by.
As for the sentence:
- He celebrates the Chinese New Year by playing fire works.
Can I drop the word by?