non-defining clauses 問題

The English book that/which is on the desk is blue.
(1) Defining Clause(定義短句)通常有Relative Pronoun(關係代名詞)，如who, whom, which, when, that, where, why等。若句子中缺少了以下句子中括號裏的短句, 整句句子便會失去原意或變成無意義：
John knows (where Tom lives).
如果沒有where Tom lives，句子就沒有意思了：John knows.
Marry will phone me (when Edward has arrived Hong Kong).
如果沒有when Edward has arrived Hong Kong，句子仍有意思，但已經失去原意。
Raymond,(the man whom we met this morning), is my uncle.
(2) Non-Defining Clause(非定義短句)當中的whom, which, when, that, where, why等只是補充加以描述，忽略此短句句子仍有意思，只是沒有加以描述。如：
The girl (who is dressing a beautiful pink dress) is one of my good friends.
如果沒有who is dressing a beautiful pink dress，就變成The girl is one of my good friends，句子仍然成立，但沒有描述到誰是我的好朋友，前句就說明了穿著漂亮的粉紅色裙子的那個女孩。

首先要明白' 定義短句'(Defining Clause)是多用'關係性代名詞'(Relative Pronoun)如 when, which, that, who, where 等作起句如以下理括孤內的短句,
句子中若缺少了這短句, 整句便會失去原意或變成無意義, 如下：
She will tell you (where she lives).
I will call you (when he arrives).
Will you let me ( how old are you) ?

2011-03-15 12:54:54 補充：
' 非定義短句'(Non Defining Clause) 雖用以描述' 主詞'(Subject), 也常用
Relative Pronoun 起句, 但原句缺了它也不失基本意思如下：
The car, (which I borrowed from a friend), was stolen.**並不一定用人名**
Matthew, ( who is a good student), is getting naughty lately(最近變頑皮了).

2011-03-15 13:05:17 補充：
Raymond,(the man whom we met this morning), is my uncle.

你的句子可寫成 The English book,(which is blue), is on the desk. 或
The English book, ( which is on the desk), is blue. 括弧中便是 Non-Defining
Clause了。視乎你句子主要表達的是' 書在桌上' 或' 書是藍色的'。

2011-03-15 14:16:45 補充：
對不起, 我在002 意見中第三句 Will you let me know ( how old are you).中漏打了 know 字。敬希原諒及留意。