【改错】Look into the reason, they asked the government to pass the law to protect the environment and keep the balance of nature.

本句至少有3种改法：

1.  使用现在分词的完成体，必须显示出时间的先后：

Having looked into the reason, they asked the government to pass the law to protect the environment and keep the balance of nature.

2. 使用after 引导的时间从句，必须显示出时间的先后：

（1）After they looked into the reason, they asked the government to pass the law to protect the environment and keep the balance of nature.

（2）After they had looked into the reason, they asked the government to pass the law to protect the environment and keep the balance of nature.

3. 使用介词 after + 动名词，必须显示出时间的先后：

After looking into the reason, they asked the government to pass the law to protect the environment and keep the balance of nature.

但是，下面的修改为错误：

Looking into the reason, they asked the government to pass the law to protect the environment and keep the balance of nature.

looking into 不等于 after looking into，前者表示跟句子的谓语动词同时进行；后者表示早于句子的谓语动词。