赞同黎老师的解答。

一个句子包含三个从句并不稀奇。我给学生讲名词性从句时就曾经造了一个句子，其中包括四种名词性从句的用法。借此机会将其贴上，供参考。

What made him angry was that I told the boss that he had let out the secret that the company was laying off some of the staff. 令他恼怒的是，我告诉老板他泄露了公司打算裁减部分人员这个秘密。

分析：

1. what made him angry为主语从句。

2. that I told the boss ...为表语从句。

3. that he had let out the secret...为宾语从句（作told的直接宾语）。

4. that the company was laying off some of the staff为同位语从句（说明secret的具体内容）。

Making a timeline that shows when different events happened (主语)//can help (谓语动词)//you(宾语)// understand how the events are connected to each other(宾语补足语).

句子主干为“Making a timeline can help you to understand how...”

以上句子整体结构为“1个动名词短语作主语”即“Making a timeline(主语)”+“that定语从句”+定语从句中嵌套“when宾语从句”+(主句)谓语动词can help+宾语you+宾补(to可以省略) understand +宾不中又嵌套1个how宾语从句。

【1】关系代词“that”引导定语从句，修饰前面名词“timeline”

【2】连接副词“when”引导宾语从句,作定语从句中的谓语动词“shows”的宾语

【2】连接副词“how”引导宾语从句，作不定式(to) understand后面宾语

备注：help sb to do sth=help sb do sth帮助某人做某事

Making a timeline that shows when different events happened can help you understand how the events are connected to each other.

【分析】

1. that shows when different events happened 是定语从句，该定语从句中的 when different events happened是一个宾语从句中，作shows 的宾语；

2. can help 是主句的谓语动词，you understand how the events are connected to each other 是宾语从句，作can help的宾语；

3. 在you understand how the events are connected to each other 这个宾语从句中，how the events are connected to each other 又是一个宾语从句，作  understand 的宾语。

【试译】

Making a timeline that shows when different events happened can help you understand how the events are connected to each other. 列一张显示不同的大事发生的时间表可以帮助你理解这些事件是怎样相互联系的。