受唐朝文化影响很大，至今还保留着唐朝人的某些风尚的国家是（    ）

①一质点在直线上以速度v=3t²﹣2t﹣1（m/s）运动，从时刻t=0（s）到t=3（s）时质点运动的路程为15（m）；

②若x∈（0，π），则sinx＜x；

③若f′（x₀）=0，则函数y=f（x）在x=x₀取得极值；

④已知函数 $f\left(x\right)=\sqrt{-x^2+4x}$ ，则 ${\displaystyle \int {}_0^{2}f\left(x\right)dx}=\pi$ ．

    Facing the Enemies Within

    We are not born with courage, but neither are we born with fear. Fears, even the most basic ones, can totally ruin our ambitions (雄心壮志). Fear can ruin fortunes. Fear can ruin relationships. Fear, if left unchecked, can ruin our lives. Fear is one of the many enemies living inside us.

    ____.

    The first enemy we face is indecision. Indecision is the thief of opportunity____. Take a sword to this enemy.

    The second enemy inside is doubt.____ But you also can't let doubt take over. Many people doubt the past, doubt the future, doubt each other, doubt the government, doubt the possibilities and doubt the opportunities. Worse of all, they doubt themselves. I'm telling you, doubt will ruin your life and your chances of success. It will empty both your bank account and your heart.____

    Do battle with the enemy. Do battle with your fears.____. Be courageous in your life and in your pursuit of the things you want and the person you want to become.

A. Sure, there's room for healthy doubt. You can't believe everything.

B. Build your courage to fight what's holding you back, what's keeping you from your goals and dreams.

C. Let me tell you about two of the other enemies we face from within.

D. Below are the ways which might be useful for us to overcome our fears.

E. Doubt is an enemy. Go after it. Get rid of it.

F. It will steal your chances for a better future.

G. Some people doubt everything.