participle phrase

Garlic已經答得很好，

Q1)不是prepositional phrase，因為Before/After在這分詞子句是作連詞用，但分詞子句的功用是adverbial

Q2)正如，Garlic所說1b可以不要After，但2b卻不可以，其理由正如Garlic所說；但因為分詞子句可帶出時間，理由，條件，結果，有時讀的人很難分辨，所以往往我們要加上適當的連接詞，使之更清晰，所以不宜刪掉它們。
如：

While staying in America, he lost his wife.
Though living so near his house, I seldom see him.

Q3)在我個人的經驗看，1b/2b的after/before應是連詞

Q4)On 確是preposition

Q5)這個問題也曾出現在我心中，在介詞後的是分詞還是動名詞呢？故我曾寫信去英文專欄問，並得到以下答覆：

On arriving in Chicago 等 於 on his arriving in Chicago 或 on his arrival in Chicago ，可 見 把 arriving 當 作 （ 動 ） 名 詞 是 不 無 道 理 的 。 英 語 學 者 斯 旺 （ Michael Swan ） 的 《 英 語 用 法 指 南 》 （ Practical English Usage ） Participles: clauses 一節 有 一 句 話 ， 或 可 解 答 讀 者 的 問 題 ： Note that -ing forms after prepositions can often be considered as either participles or gerunds -- the dividing line is not clear （ 介 系 詞 之 後 的 ing 動 詞， 往 往 可 視 為 分 詞 或 動 名 詞 ， 難 以 清 楚 辨 別 ） 。 斯 旺 在 書 中 把 on arriving in Chicago 之 類 子 句 稱 為 分 詞 子 句 ， 但 顯 然 認 為 只 要 文 法 正 確 ， 子 句 應 列入 哪 一 個 類 別 並 不 重 要 ， 這 一 點 我 絕 對 贊 成 。

希望幫到你！




2011-06-17 17:48:27 補充：
其實為甚麼這樣難分，我想是因為英文是受希臘文影響，希臘文的分詞就同時具有：

英文分詞（修飾作用）和動名詞的功用

我分別PR. P 與 GERUND=V~ING的方式是看它是什麼角色.

角色是SUBJECT...OBJECT...COMPLEMENT...AFTER A PREP.=GERUND.


角色是VERB...ADJ...ADV.=PARTICIPLE.


它是什麼,相當被動,身不由已..........同一PHRASE可以是演繹不同的角色.是要看它擺在什麼位置.

Although my English isn't good, I've some opinions in this topic.

I don't think it's hard to distinguish if ing form is a gerund or an adjective. Look at you guys' example:

While speaking on the phone, she doodled.

2011-06-17 20:49:46 補充：
It means: While she was speaking on the phone; she doodled. Thus speaking is an adjective instead of a gerund.

The suspect is tried for killing two women.

This example is more clear. Killing is a gerund it couldn't be an adjective.

2011-06-17 20:53:01 補充：
By appealing to the emotion of the public, the advertisement achieves its end.

Appealing is an adjective, because appealing this word appears in an adjective phrase to describe the advertisement.

2011-06-17 20:53:26 補充：
Ho-yin, On + -ing 是 prep+NP 組成一個 PP
而, After/berfore + -ing 是 conj + non-finite ...

I don't think your way of learning English works, because we have to understand the whole sentence meaning. We have to learn English in many ways. Grammar is only one part of English.

2011-06-18 11:47:45 補充：
Can you provide us examples?

John resigned this Monday, leaving his followers stunned at how his bright future could be.

How do you explain the roles of "leaving" and "stunned"?

我有一點懷疑, 我們學-ing 形式時, 把它二分為participle和gerund的這種做法,其實根本不恰當, 因為出現了難以區分二者的情況. 它們的二分這一概念尚未圓滿.

2011-06-17 19:14:26 補充：
hahatse:

其實我也看過 Practical English Usage 一書.
這書也說到寧願叫它做-ing形式, 而不叫做動名詞/分詞
似乎英文中"動名詞/現在分詞"這兩個叫法真的有模糊的地方.

不過即使放棄"動名詞/現在分詞"這兩個叫法, 統一地叫做ing形式,
我仍可以問它是noun phrase 還是non-finite clause.

2011-06-17 19:15:18 補充：
照大家的意見, On + -ing 是 prep+NP 組成一個 PP
而, After/berfore + -ing 是 conj + non-finite clause

如果大家都沒有異議的話,
我下一個問題將會是 如何判斷一個類似的結構屬哪一類.

I shall answer with the best of my knowledge.

Q1. I am not a grammarian, I don't know if the phrases in bold type are prepositional phrases. One thing is for sure, they are adverbial phrase.

Q2. After can be removed from (1b) but the sentence should be written like this:
Having returned my library books, I borrowed some magazines.

Before cannot be removed from (2b). A participle phrase implies a causal or sequential relation. The event in the participle phrase takes place before the event in the main clause, as in this example:

Feeling hungry, Sue searched the cabinets for food.

In (2b), switching off the lights occurs before going out. Without before, the sequence of events are reversed.

Q3. In (1a) and (2a), after and before are conjunctions. In (1b) and (2b), they are prepositions.

Q4. On is a preposition in (3).

Q5. being is a participle, not a gerund.

2011-06-17 16:05:44 補充：
關於問題五 hahatse所言甚為有理。多數情況下介詞後的-ing 可以用名詞替代
Practice is crucial for developing good skills.
Practice is crucial for the development of good skills.

The suspect is tried for killing two women.
The suspect is tried for the killing of two women.

這情況下-ing 應視為gerund。

2011-06-17 16:34:04 補充：
有些句子-ing 難被名詞替代
The advertisement works by appealing to the emotion of the public.
appealing應是gerund。

By appealing to the emotion of the public, the advertisement achieves its end.
gerund還是participle就比較模糊了。

Appealing to the emotion of the public, the advertisement achieves its end.
participle無疑。

2011-06-17 16:46:30 補充：
On receiving the invoice, payment should be made immediately. 可寫成
On the receipt of the invoice, payment should be made immediately.
按我在意見(2)的引伸，問題五的being 確應視為gerund。

2011-06-17 16:53:41 補充：
While speaking on the phone, she doodled.
speaking 不可能是動名詞。speaking 在句中是一個 non-finite verb
While 是作連接詞之用，不是介詞。

2011-06-17 16:58:16 補充：
同意 hahatse 講，(1b) (2b) after, before 是conjunction，所以其後的 -ing 是participle。