当，化简$\sqrt{{\left(x-1\right)}^2}$=（     ）。

阅读理解。

    Many teenagers feel that the most important people in their lives are their friends．They believe that their family members, especially their parents, don't know them as well their friends do．In large families, it is often for brothers and sisters to fight with each other and then they can only go to their friends for advice．It is very important for teenagers to have one good friend or many friends．Even when they are not with their friends, they usually spend a lot of time talking among themselves on the phone．This communication is very important in children's growing up, because friend can discuss something difficult to say to their family members.

    However, parents often try to choose their children's friends for them．Some parents may even stop their children from meeting their good friends．The question of “choice” is an interesting one．Have you ever thought of the following questions?

    Who choose your friends?

    Do you choose your friends or your friends choose you?

    Have you got a good friend your parent don't like?