题目内容：

根据句意和中文注释，在答题卷相应的横线上写出所给单词的正确形式。

1.It is well known that UNICEF is an __________________ (国际) organization.

2.Tom has gone to America on ___________________(出差).

3.As the saying goes，”_____________(知识) is power.”

4.How many years’ _______________(经验)do you have of teaching English?