集合M={a,b},N={a+1,3}，a,b为实数，若$M\cap N=\left\{2\right\}$，则$M\cup N=$(　　)

    ____between people of different countries. The super star Jay Chou has cooperated with the American NBA star Kobe Bryant to create a song named The Heaven and Earth Challenge.____ It expresses the love for basketball.____ Jay Chou has learned much from Kobe's sports spirit. In the song,____ People can download the ring tone(铃声) of the song from the Internet.____ which aims to improve educational environment in poor areas in China

A. And it encourages young people to be more confident.

B. Music touches our hearts and shortens(缩短) the distance

C. Jay Chou does most of the singing part while Kobe plays a part of a rapper(说唱者).

D. All the money from the downloads will go to Project Hope.

E. That's a song written by Jay Chou whose favorite sport is basketball.

下列所示的杠杆中，属于费力杠杆的是（     ）

下列关于地球大小的说法，错误的是（    ）