根据句意，用所给单词的适当形式填空。

1．It gives us much________（please）to welcome our new teacher．

2．We are looking forward to ________ （visit）Shanghai World Expo．

3．Thanks for your________ （invite）．I'll be there on time．

4．This was one of the worst________ （nature）disasters in the history of the United States．

5．Students at school shouldn’t get their ears________ （pierce）．