### Теорія:

Study some signal words for Past Perfect Continuous.

Words for Past Perfect Continuous:

for — протягом;

since — з, з того часу;

when — коли;

how long — як довго;

before — до того.

Examples

In $$2014$$ The Browns had been living in London for twenty years.

I had been working for this company since $$2017$$.

We had been waiting for Mary since morning when she finally arrived at $$5$$ pm.

They had been watching TV when the lights went off.

How long had you been waiting before he came?

James had been teaching at the university for more than a year before he left for London.
Джерела:
nit.pt/out-of-town/viagens/8-hoteis-incriveis-para-dormir-em-londres-por-menos-de-70e
www.moneycrashers.com/watch-free-hdtv-channels-digital-tv-antenna/