例：by doing something
This structure looks like: “by doing /being something, we do/are…”. It is used when two things are true of the subject, and one of those things causes the other.
1. The By + gerund Phrases must be about the subject of the clause.
2. The action of the gerund is done by the subject of the sentence.
1. By being well prepared, we can overcome any obstacle.
2. By not turning off your cell phone, you are inviting interruptions.
3. By hurrying up, we can reach the ice cream shop before it closes.
4. By drinking enough coffee, I can prevent myself from falling asleep in class.