根据句意及提示写单词。

1. My parents are celebrating 30 years of their m_____.

2. Beijing is the c_____ center of China.

3. The elephant waved to us with their t_____ and ears.

4. Wish you _____ (成功).

5. Let's _____ (讨论) how to work out the Maths problem.

6. —How many _____ (表演者) are there ion the show?  

    — I'm not sure.