依据图①﹣④，下列说法错误的是（　　）

${\int }_0^{\frac{\pi }{2}}{\sin }^2\frac{x}{2}dx=$(   )

在$△ABC$中，角A,B,C所对边长分别为a,b,c，若$a^2+b^2=2c^2$，则cosC的最小值为（    ）

    There are so many expressions in American English that sound pleasant (令人愉快的)but are not. ____ When someone says they have to "face the music", it does not mean they are going to a concert. "Facing the music" means to accept and deal with the punishment of an action.

    ____ For example, "I can't face another night of camping! It's cold and rainy." Or "In life, you must face your fears." Face used in this way is very common.But now, let's go back to facing the music. Imagine a friend asks you to take care of her beautiful red sports car. She gives you the keys and says, "Thanks so much for watching my car while I'm away. But please, do not drive it. It is an extremely (极其) fast car." ____ You want to show off to some friends. So, you drive it around town one night. As bad luck would have it, you lose control of the car and drive it into a stop sign. Bang!

    When your friend returns you must tell her what you have done and "face the music". ____ It could be losing her friendship or paying for repairs to her sports car or both. Whatever the music is, you must face it.

    ____To "take your medicine" means to accept the results from something bad you have done. And if someone says, "You made your bed. Now lie in it." they mean you created a bad situation and now you will experience the results!

A. But you do not listen.

B. "Face the music" is a good example.

C. The "music" here is the result of your actions.

D. Americans often use the word "face" in this way.

E. There are other American expressions that mean the same thing as "face the music".