已知$\alpha$是第二象限，且$\sin \left(\mathrm{\pi }+\mathrm{\alpha }\right)=-\frac{3}{5}$，则$\tan 2\alpha$的值为(   )

— What is ______ favorite color?

— Purple. Look! My watch is purple.

    Do you know Chen Yixun? He is a great singer from Hong Kong. He has a lot of beautiful songs, so many people love him. This year Chen Yixun gives concerts (演唱会) in some cities in China. And on November 7 the concert is in Jiaxing.

    Chen Yixun wants to give great concerts, and he does a lot of work for that. First, he practises singing every day. And he always drinks warm water. There are also dances at the concerts, so he needs to practice dancing, too. It's a hard job. Then, he also needs to do exercise like running and swimming. He has to be healthy and strong for the concerts.

    “I have a busy life, but I love it. I enjoy singing and I wish to give great shows to people,” says Chen Yixun. Wish him good luck!