Tuesday, August 31, 2010

Past Perfect

I was recently asked which of the following was correct:

(a)  Before I left the room, I switched off the lights. (simple past)
(b)  Before I left the room, I had switched off the lights. (past perfect)

My reply was that (a) was correct, but I was told that (b) was given as the recommended answer in a primary school English exercise.  However, I have no doubt that (b) is definitely wrong.

In Standard English (StdE), the simple past is used for events that may be represented as a single point on a time line showing present time and past time.  It tends to be used when there is a specific time expression, e.g. yesterday, three hours ago.  If we represent this on a time line, we need two points: one indicating present time, and another indicating yesterday or three hours ago.

The past perfect, by contrast, is used when referring to the earlier of two or more events. If on a time line we have three points A, B and C, where C is present time, the later past event B will be expressed in the simple past, whereas the event that preceded it, Event A, will be expressed in the past perfect.

The past perfect is properly used below:

(c)  He popped by, but I had already left the room.

In Singapore, the past perfect is often incorrectly used, perhaps because of a poor understanding of what constitutes an ‘earlier past event’.  Admittedly, it is not always easy to determine what an earlier past event is, and the proposition expressed in (a) and (b) is a good case in point: doesn’t switched off the lights qualify as an earlier past event, since it took place before left the room?

The explanation is not so straightforward, and lies in the fact that before I left the room counts as a specific time expression — hence the use of simple past switched as in (a) rather than past perfect had switched as in (b).  Note that before I left the room is a subordinate clause; it cannot stand alone and has to be attached to a main clause, in this case I switched off the lights.  Note also that, as is typical of subordinate clauses, it can be moved around: I switched off the lights before I left the room means the same thing.  Another thing: it is an adverbial, like so many subordinate clauses are, and as it conveys time, it is a adverbial of time.

Contrast this with (c), which has two main clauses, He popped by and I had already left the room, either of which can stand on its own.  Unlike subordinate clauses, main clauses cannot be inverted freely, hence *I had already left the room but/and he popped by is ungrammatical, or at best very odd.  Hence, either main clause expresses an independent past event; neither serves as a time adverbial to the other.

3 comments:

Fox said...

"Note that before I left the room is a subordinate clause; it cannot stand alone and has to be attached to a main clause, in this case I switched off the lights. Note also that, as is typical of subordinate clauses, it can be moved around: I switched off the lights before I left the room means the same thing. Another thing: it is an adverbial, like so many subordinate clauses are, and as it conveys time, it is a adverbial of time."

Why does it being a subordinate clause/adverbial exclude the use of the past perfect? Is there a grammar textbook you can refer to?

I'm pretty sure that I've seen, in the US by native speakers, sentences of the form: A had done X before A did Y.

The Grammar Terrorist said...

Because subordinate clauses cannot stand on their own, they are in effect incidental to the main clauses they're attached to. So, in essence, the main clause presents the main information or proposition, whereas the subordinate clause adds additional, circumstantial information.

Yes, I think it's easy to set up a context where "A had done X before A did Y" -- but in isolation, the simple past is more appropriate in the sentence I gave. Admittedly, context is always an issue when questions appear in a test and hapless students need to guess or have very different (but equally valid) interpretations of the context.

Your example would be perfectly normal here: "I left the room at about 10. At 10.15 I returned to check. I was pretty sure that before I left the room, I had switched off the lights, but I just wanted to be absolutely certain".

GM said...

Dear GT

The following is from http://www.channelnewsasia.com/stories/afp_asiapacific/view/1083993/1/.html ,29 Sept 2010.

SEOUL: The youngest son of North Korean leader Kim Jong-Il has been given senior posts in the ruling communist party, state media said on Wednesday, confirming his status as heir apparent to his ailing father. 

Kim Jong-Un was named a member of the party's central committee and vice-chairman of its central military commission, the Korean Central News Agency (KCNA) said. 

On Monday the 68-year-old leader had appointed his son a four-star general in another confirmation he has been picked as eventual leader of the impoverished but nuclear-armed nation. 

I find the past participle in para three strange.

Thanks ,GM.