1. Lesson 12 (Dec. 1) Relative Clauses (2)

2. Relative Clauses Recall: – Relative clause which follows the subject noun of the main clause:  An object which is left in the sun becomes hot. – Relative clause which follows the object noun of the main clause:  This paper is made from alfalfa which is expensive. – Prepositional relative clauses:  The river from which this water is taken is polluted.  That farm produces alfalfa from which this paper is made.

3. Relative Clauses with whose & of which main clause Example: – Venus is a planet. – The surface temperature of the planet is at least 200°C. 1.Venus is a planet (the surface temperature of the planet is at least 200°C). 2.Venus is a planet of which the surface temperature is at least 200°C. 3.Venus is a planet whose surface temperature is at least 200°C. Both whose and of which are acceptable here. However, whose is usually reserved for people. In the above example, Venus is treated as a person.

4. Relative Clauses with whose & of which Example:  The rectifier is an electronic device.  The effect of the device is to restrict current to one direction. Using whose on an inanimate object is not acceptable:  The rectifier is an electronic device whose effect is to restrict current to one direction. In such cases, always use of which :  The rectifier is an electronic device of which the effect is to restrict current to one direction. main clause

5. Relative Clauses with whose & of whom Example:  Einstein was a 20 th Century physicist.  His Theory of General Relativity was an important discovery. For a person, whose is the obvious choice:  Einstein was a 20 th Century physicist whose Theory of General Relativity was an important discovery. Very rarely, one may also use of whom :  Einstein was a 20 th Century physicist of whom the Theory of General Relativity was an important discovery. Of which is never used on a person. main clause

6. Passive relative clauses are sometimes reduced: Our first example:  An object is left in the sun. It becomes hot.  An object which is left in the sun becomes hot.  An object left in the sun becomes hot.  Another example:  Paper which is made from alfalfa is expensive.  Paper made from alfalfa is expensive. Reduced Relative Clauses

7.  Paper made from alfalfa is expensive. Notice that only which + be and who + be can be reduced, i.e. which is, which are, which was, which were. We use reduced passive relative clauses because they are shorter and because which is or which are are uninformative. Our other examples:  A bottle which is dropped on a stone floor usually breaks into pieces.  A balloon which is filled with a gas lighter than air rises off the ground.  A diseases which is caused by a virus is often difficult to cure. made is not a verb here. It is a past participle. One can think of it as an adjective describing the paper.

8. Reduced Relative Clauses Not all passive relative clauses can be reduced. Passive relative clauses beginning with a preposition cannot be reduced. The following reduction is wrong!  The tarmac with which these roads are surfaced allows higher speed than stones.  The tarmac with these roads are surfaced allows higher speed than stones.

9. Like passive clauses, active relative clauses in scientific English usually begin with which. They can also begin with who, where, whose, that, or a preposition+ relative. The Ford iMax is a mid-size family car. It seats 5 people. The Ford iMax is a small family car which seats 5 people. The man teaches physics. He is a graduate of NCNU. The man who teaches physics is a graduate of NCNU. The room has only one small table. He works in the room. The room in which he works has only one small table. Active Relative Clauses

10. Reduced Relative Clauses Some active relative clauses can also be reduced.  The man who teaches physics is a graduate of NCNU.  The man teaching physics is a graduate of NCNU. In this case the wh-word (which, who, etc.) is omitted and the verb is changed to a present participle (verb+ ing ): which/who verb  verb+ ing  He has a form of cancer which requires surgery.  He has a form of cancer requiring surgery.

11. Reduced Relative Clauses  The man who teaches physics is a graduate of NCNU.  The man teaching physics is a graduate of NCNU. The above reduction is applied when the wh- word is the subject of the verb that follows it. ▪ “who” is the subject of the verb “teaches”. ▪ “who” replaces the subject “He” in the original secondary clause: He teaches physics. ▪ When the wh -word is the object noun of the verb that follows it, the wh- word can be simply omitted without any change to the verb:  This is the pen which he uses.  This is the pen he uses.

12. Other wh- words Where is used for places in passive relative clauses, and is a substitute for in which, at which :  The room has only one small table. He works in the room. The above can be rephrased in two ways: The room in which he works has only one small table. ‚The room where he works has only one small table. Another example:  I often go to the library. I can find many interesting books in the library.  I often go to the library in which I can find many interesting books. ‚ I often go to the library where I can find many interesting books.

13. Other wh- words wherein = in which – A university wherein students are excited about learning is a good university. whereby = by which – A waveguide is a structure whereby signals can be transmitted. – The paper proposes a method whereby the filter’s performance can be optimized. whereby = because of which – The university has introduced a new rule whereby all TAs must undergo training.

14. That instead of wh- words The wh- words we have discussed are called relative pronouns, i.e. subject or object nouns in relative clauses.  subject:An object which is left in the sun becomes hot.  object:This is the pen which he uses.  subject:The man who teaches physics is a graduate of NCNU.  object:The room where he works has only one small table. In some relative clauses, that is used as the relative pronoun instead of a wh -word:  This is the best movie that I have seen.  The terms that have been omitted in the equation are negligible.

15. That instead of wh- words As a general rule, that is used in a relative clause referring to persons or things that you are defining:  The terms that have been omitted in the equation are negligible. – The above relative clauses tells the reader about those terms for the first time. That is also used where the person or thing is specific:  This is the best movie that I have seen.

16. That versus Which American academics and editors are especially particular about when to use that, and when to use which. The traditional approach to this question is to use that with restrictive relative clauses and which with nonrestrictive relative clauses. A restrictive clause restricts the identify of the subject:  The painting that was hanging in the room was stolen.  Without the restrictive clause, the reader would not know which painting you are talking about. A nonrestrictive clause may tell us something interesting about a subject, but it does not define that subject. The subject probably has already been mentioned before.  The painting, which was hanging in the foyer, was stolen.

17. That versus Which That! Which! More about this in 科技英文 ( 二 )

18. Nested Relative Clauses Nested relative clauses combine more that two simple sentences: We are asked to read a paper. ‚The paper was written by a graduate student. ƒThe student studies composite materials.  The paper was written by a graduate student who studies composite materials.  We are asked to read a paper which was written by a graduate student who studies composite materials.

19. Nested Relative Clauses Reduced relative clauses are especially useful in such cases:  We are asked to read a paper which was written by a graduate student who studies composite materials. Reduced: We are asked to read a paper written by a graduate student studying composite materials.