Hybridoma Technology ( Production , Purification , and Application )
Past perfect
1. PAST TIME
Before a time in the past
When we talk about something that happened in the pastwe sometimes want to refer back to something
that happened before thattime.
We can use the past perfect tense (had + past participle).
Past perfect
These sentences
John left the house at 7:30 yesterday morning.
Mary rang John’s doorbell at 8:15 yesterday.
Express actions happened in the pastso we use the past simple tense.
But, if we want to combine the sentences.
Mary rang John’s doorbell at 8:15 yesterday but John had already left the house.
We use the past perfect (had left) because the action happened before another action in the past(Mary
rang the doorbell.)
Look at some more examples ofthe past perfect.
When Mrs Brown opened the washing machine she realised she had washed the cat.
Look at these 2 sentences.
James had cooked breakfast when we got up.
James cooked breakfast when we got up.
In the first sentence, the pastperfecttells us that James cooked breakfast before we gotup.
In the second sentence,firstwe gotup and then James cooked breakfast.
2. Examples:
You had studied Englishbeforeyou movedto NewYork.
Had you studied Englishbeforeyoumovedto NewYork?
You had not studied Englishbeforeyou movedto NewYork.
PAST PERFECT USES
USE 1
Completed Action Before Something in the Past
The Past Perfectexpresses the idea that something occurred before another action in the past. It can also
show that something happened before a specific time in the past.
Examples:
I had never seen suchabeautifulbeachbeforeI wentto Kauai.
I didnot have anymoneybecauseIhad lostmywallet.
Tonyknew Istanbulso wellbecausehe had visited thecityseveral times.
Had Susan ever studied Thaibeforeshemovedto Thailand?
She onlyunderstoodthe moviebecauseshe had read thebook.
Kristinehad never been toan operabefore last night.
We were not ableto get a hotel room becausewe had notbooked inadvance.
A: Had you ever visited theU.S. beforeyour trip in 2006?
B: Yes, I had been tothe U.S. oncebefore.
USE 2
Duration Before Something in the Past (Non-Continuous Verbs)
With Non-Continuous Verbs and some non-continuous uses of Mixed Verbs, we use the PastPerfectto
show that something started in the pastand continued up until another action in the past.
3. Examples:
We had had that carfor ten years beforeit broke down.
By the time Alex finishedhis studies, he had been inLondonfor over eightyears.
Theyfelt badaboutsellingthe housebecausethey had owned it for morethanforty years.
Although the above use of Past Perfectis normallylimitedtoNon-ContinuousVerbs andnon-continuoususesof
MixedVerbs, the words"live," "work," "teach," and"study" aresometimesusedinthis way even though they areNOT
Non-ContinuousVerbs.
IMPORTANT Specific Times with the Past Perfect
Unlike with the PresentPerfect, it is possible to use specific time words or phrases with the Past Perfect.
Although this is possible, itis usually notnecessary.
Example:
She had visited herJapaneserelativesoncein1993beforeshe movedin with them in 1996.
MOREOVER
If the Past Perfectaction did occur ata specific time, the Simple Pastcan be used instead ofthe Past
Perfectwhen "before" or "after" is used in the sentence. The words "before" and "after" actually tell you
what happens first, so the Past Perfectis optional. For this reason, both sentences below are correct.
Examples:
She had visited herJapaneserelativesoncein1993beforeshe movedin with them in 1996.
She visited herJapaneserelativesoncein1993beforeshe moved inwith them in 1996.
4. Past Perfect Continuous
FORM [had been + presentparticiple]
The past perfect can also be used in the continuous.
I realised I had been working too hard so I decided to have a holiday.
By the time Jane arrived we had been waiting for 3 hours.
We should remember that, we only use the past perfectwhen we want to refer to a past that is earlier than
another time in the narrative.
Examples:
You had been waiting thereformorethantwo hours whenshe finallyarrived.
Had you been waiting thereformorethan two hourswhenshe finallyarrived?
You had notbeen waiting thereformorethantwo hourswhenshe finallyarrived.
USE 1
Duration Before Something in the Past
We use the Past PerfectContinuous to show that something started in the past and continued up until
another time in the past. "For five minutes" and "for two weeks" are both durations which can be used with
the Past PerfectContinuous. Notice that this is related to the PresentPerfectContinuous; however, the
duration does notcontinue until now, it stops before something else in the past.
Examples:
Theyhad been talkingforover anhour beforeTonyarrived.
She had been workingatthat companyfor three years whenit went out of business.
Howlong had you been waiting toget onthe bus?
Mikewantedto sit downbecausehe had been standing alldayat work.
Jameshad been teaching attheuniversity for morethana year before heleft for Asia.
A: Howlong had you been studying Turkishbeforeyou movedto Ankara?
B: I had notbeen studying Turkishverylong.
5. USE 2
Cause ofSomething in the Past
Using the Past PerfectContinuous before another action in the pastis a good way to show cause and
effect.
Examples:
Jasonwas tired becausehe had been jogging.
Betty failedthe finaltest becauseshe had notbeen attendingclass.
ADVERB PLACEMENT
The examples below show the placementfor grammar adverbs such as: always, only, never, ever, still, just,
etc.
Examples:
You had onlybeenwaitingtherefor a few minuteswhenshe arrived.
Hadyou onlybeenwaitingtherefor a few minuteswhenshe arrived?