Please,
What is the main difference betwenn PAST PERFECT and PAST PERFECT CONTINUOUS, I mean, how to explain it to the students ?
:up:
The difference is similar to that between the present perfect and pres. perf. continuous.
I have driven / I have been driving. (pres. perf.)
I had driven / I had been driving. (past perf.)
Present perfect:
"I have driven a bus before, so I think I can take these people on a short trip."
"I have been driving a bus ever since I got my licence, so I'm not worried about driving in heavy traffic."
Past perfect:
"I had driven along that route before, so I knew the way."
"I had been driving along that route for three years, so I knew the roads like the back of my hand."
The continuous, as usual, simply adds the element of ongoing-ness to the verb.
With continuous tenses, something
is happening,
was happening, or
had been happening in the same situation that the non-progressive tenses describe something that happen
s,
did happen or
had happened.
It's often used to describe a situation in which something was happening (over a period of time) when something interrupted it. A discrete event interrupts an ongoing event:
"I'm walking along, minding my own business, and some guy comes up and mugs me." (present continuous -> present simple)
"I was watching television when the phone rang" (pres perf. cont. -> simple past)
"I had been working there for 20 years when they decided to sack me" (past perf. continuous -> simple past)