1 . The class became a circus as the boys, ________ ________ ________ ________ ________anything like this before, started jumping out of the windows.
班上乱成了马戏团，男孩们纷纷跳窗跑走，因为他们以前从没遇到过像这样的事情。

2 . 他是一个忠实的倡导者，强烈倡导使用清洁能源，如太阳能、风能等，而不是使用那些污染我们环境的能源。（advocate，应用定语从句）
He is a devoted advocate, ________clean energies such as the energy of the sun, the wind and etc. ________using whose that pollute our environment.