There are no regrets in life, just lessons.
人生中没有后悔，只有教训。
Some people can learn from their past mistakes and never make the same mistake again.
But some people only regret for their past failures and seldom learn lessons from their negative experience, they may fall down at the same points again and again.
Today, I have spent nearly three hours on writing this post, I am sure that such behaviours may have no use in my life.
I want to stop making such useless efforts, and I want to spend more time on my major, like how to perfect my program, how to imporve my coding skill.
Ok, let's stop to write some codes, which will run on the embedded system.
You cannot shake hands with a clenched fist.
握紧拳头时，你是无法握手的。
From Indira Gandhi.
Indira Gandhi, the late powerful politician of India from the Nehru-Gandhi family, was born on November 19th 1917 and dead on October 31st 1984.
She was one of the most influential politician of India and a great figure of the Indian National Congress Party, and the first and to date the only female Prime Minister of India.
She served as the Prime Minister in 1966 to 1977 and then again from 1980 until her assassination in 1984.
As the Prime Minister of India, Indira was known for her political ruthlessness and unprecedented centralisation of power.
And she went to war with Parkistan in support of the independence movement and war of independence in East Parkistan, which resulted in an Indian victory and the creation of Bangladesh, as well as increasing the influence of India to the highest point where it became the regional hegemony in South Asia.
If the policies of Indira Gandhi could be continued for tens of years, India would be quite different from its current condition, I mean, it may become a country with huge global influence.
Back to this sentence from her, you can't shake hands with a clenched fist, even if someone reaches his hand to you, he would withdraw his hand if he sees your clenched fist.
If we want to get acquaintance with strangers, it would be better to reach out our hands first.