present and past perfect tense

[venkatasu]

Please read the following passage.

Over the last twenty years, the average size of households has fallen dramatically. The number of one person households has grown, due largely to the ageing of the population, as has the number of one parent families. Couples having smaller families have also contributed to the fall in household size.
In 1976, 60% of families were couples with children. By 1996, this had fallen to 51%. Part of this change can be attributed to the increase in one parent families with dependent children, but most of the change is due to the increase in the proportion of couple only families. People are now having children later in life, and are living longer. Therefore, they are spending more time living in couple-only families, both before they have families and after their children have left home.
However, children are leaving home later. In 1981, 34% of children aged 20-24 lived with their parents. By 1991, this had increased to 40%. This increase has, to some extent, countered the fall in the couples with non-dependent children only.
(Source: ABS Yearbook Australia 1997, Number 79 p. 81)

Source : Past Perfect Exercise

In this site they have given an exercise to find past perfect verb using the above passage. I know the answers. But the question is - I want to know the context for the usage of past perfect tense (as well as present perfect tense if any in the above passage) with explantions - reg this passage.

Thank you

[venkatasu]

I request visitors to answer my thread above in the context of the thread posted by Mr.MikeNewYork (in one of the past threads - thanks to his explanation). I need a similar explanation as given by Mr. MikeNewYork wherever past perfect (present perfect) tense is used in the above passage.
Thank you

Re: has or had
Quote:
Originally Posted by jack
It has rained for two days. <--correct?
It had rained for two days. <--correct?

what is the difference between the two?
When would i use the first one and the second one? Are both of these sentences correct? Should i use "has" for both of them because of the unspeficied time and you would use had for specific time.
If i can use has for both of the sentences above, then what is the point of having the rules for had and has, like had is for used specific times?


The first (has) is present perfect. In this case, it refers to recent rains. The rain probably has stopped, but there are present consquences.

The grass is still wet. It has rained for two days.

If it has rained for two days and it is still raining, one would usually say "It has been raining for two days."

The second (had) is past perfect. This is used to describe an event that was completed before another time reference.

Last year I almost drowned when I fell into an old well. The well was full of water because it had rained for two days. [The rain occurred before the speaker fell].

Quote:
It had rained on April 26.
It has rained on April 26. <-- is this incorrect? why? if the above two is correct, why isn't this one correct too?
The second is incorrect. We don't use present perfect with specific days/times. The reason is that it refers to an event that occurred in the past on a particular day. It is a simple statement of fact. We use past tense for that.

We can use the past perfect with a specific date if that date is before another event in the past.
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