系统功能语言学

You can often see that a long expression functions as a single element in a clause by trying one of the following tests:
existential clauses
An existential clause can be recognised by the presence of there, when there does not function to express a location. e.g. There is an apple tree there. An existential clause introduces a participant into the text. Although there serving as Subject does not itself function as a participant ( or circumstance ) it still is regarded as topical theme.
It was Rabbit who saw Piglet first: Rabbit saw piglet first.
2.There's a......:'Existential' clauses
There' s always a long queue. There was trouble at the mill. There might come a time....
e.g. At Sezana, on the Yugoslav border, they were very naughty, too. 3. Embedded Wh- clause as Theme.
e.g. What he ate that night gave him terrible heartburn.
e.g. It was Rabbit Theme
who saw Piglet first. Rheme
There is no varient where the embedded clause functions as Theme in this structure.
Who saw Piglet first was Rabbit. (×) Rather, the agnation is with a non-predicated version:
4. Embedded non-finite clause as Theme. e.g. Doing twenty sit-ups a day will improve your tummy muscles. It is also possible for a complex of clauses to be embedded in this way. e.g. Getting plenty of exercise and eating the right food is important. 5. Embedded 'that' clause as Theme. e.g. The fact is that the food might not be fresh.
The most typical case is when a Wh- clause is set up as Theme in a relational clause structure. e.g. What he said is nonsense. What they lacked was a business plan.
(3) Anticipatory it (mental and relational clauses) The anticipatory it serves to anticipate an embedded clause occurring later in the structure. Unlike the impersonal projections, these structures have a variant where the embedded clause is Theme. e.g. It worries me that he's not doing his homework: That he's not doing his homework worries me. (4) Anticipatory it in Theme predication Theme predication:There is another thematizing structure that allows the speaker to pick out a single element and give it emphatic thematic status. This structure singles out one experiential element to serve as both Theme and New.
Types of 'contentless' Subject it (1)Ambient it The ambient it serves as a participant in the transitivity structure of the clause. It represents the ambient conditions. e.g. It is hot. topical Theme Rheme Consequently, it can be probed with what in a whinterrogative clause. e.g. What is hot? topical Theme Rheme It alternates with fully lexicalised groups. e.g. The room is hot. topical Theme Rheme
It is not difficult to recognise an unmarked Theme when that Theme is constituted by a pronoun, such as They , or a relatively short nominal group(i.e. noun phrase), such as The big, bad wolf. However, the Theme may be realised by a longer unit than this in the following cases： 1. Nominal group inTheme position extends beyond the main noun. e.g. A large black wolf with yellow fangs spoke to Red Riding Hood.
Inrtoduction
Subject it as unmarked topical Theme
There's a......:'Existential' clauses
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Recognising longer Theme units
'Hypotactic' clause as Theme
1.Subject it as unmarked topical Theme
e.g.
There topical Theme
is a book on the desk. Rheme
topical Theme Is there a book on the desk? interpersonal Theme Rheme
3.Recognising longer Theme units
The teacher who understood him best was Marianne Fawley. 2. Group and Phrase complexes in Theme position. Sometimes more than one nominal group functions as the Theme. e.g. Jack and Jill went up the hill. Nelson Mandela, the newly elected President of South Africa, was invited. Prepositional phrases may be 'complexes' functioning as Theme. similarly linked into
commonly found in the Rheme, but do occur in Theme position.
e.g. That the food might not be fresh didn't occur to them.
Tests to check for longer Themes
Why do we still interpret this non-representational it as topical Theme? a. The mood selection of clause As unmarked topical Theme, it serves to give the mood selection thematic status. e.g. Is it raining today? inter. Theme topical Theme Rheme Is it said that he's wealthy? inter. Theme topical Theme Rheme b. It contrasts with marked topical Themes in the same way as prototypical, representational unmarked topical Themes do: It is raining today: Today it is raining. marked topical Theme Rheme
Conclusion: Ambient it is thus a perfectly regular unmarked topical Theme: it serves as Subject and has a role in the transitivity structure of the clause. （2）Non-representational it It does not represent some phenomenon of experience and does not serve a participant role. This occurs in 'meteorological' clauses and in the 'impersonal' use of it. e.g. It is raining today. (precipitation) topical Theme Rheme P.s. It doesn't represent some aspect of the environment and doesn't serve a participant role. It is said that he is very wealthy. (impersonal projection) topical Theme Rheme
As with non-representational it, there functions as unmarked topical theme, giving the mood choice( of declarative or interrogative) thematic status.