My kids are watching TV when I get home. 我回家时，孩子们正在看电视。

(1) 主语改为 She 开头的过去时

—> She was watching TV when I got home. 我回家时，她正在看电视。

(2) 改为将来进行时的句子

—> My kids will be watching TV when I get home. 我回家时，孩子们会是在看电视。

(3) 改为用 What 开头的过去进行时疑问句

—> What were my kids doing when I got home? 我回家时，孩子们在做什么？

 I turn off the light. 我关灯。/ 我熄灯。

(1) 改为过去时否定句
—> I didn't turn off the light. 我没熄灯。

(2) 改为以 you 为主语的过去时疑问句
—> Did you turn off the light? 你熄灯了吗？

(3) 改为以 I wonder if 开头的句子
—> I wonder if I turn off the light. 我有没有关灯？