在下列各句的空白处填入一个最适当的词，使句子意思完整、语法正确。

1．His grandpa is __________. He can’t hear anything.

2．In e-mail English, a happy face is made with a colon and a right bracket __________ it.

3．You aren’t supposed to __________at others with your chopsticks.

4．---Thank you very much for helping me.

    ---It’s my __________.

5．Li Yundi learned to play the piano by __________ at a very young age.