3. читав/читавши = reading (for the sentences in the past) - nowadays "читая" is used instead in all tenses.
Originally Posted by Antonio1986
Examples:
1. Работая медсестрой, она поняла, что хочет стать врачом = Working as a nurse, she understood, that she wants to become a doctor.
--- Explanation: The two actions occur the same time
2. Прочитав/ Прочитав письмо, она начала плакать = Having read the letter, she started crying.
--- Explanation: The first action was completed, and immediately after the second action took place.