Examples: Did you work at your English Yesterday? – Yes, I did.
How long had you been working at your English before you went for a walk?(for an hour )- I had been working at my English for an hour.
1.Did it rain yesterday?........ . How long had it been raining when you left home?(for 3 hours)....... . 2. Did she work at the University before she retired?......... . How long had she been working there before she retired?(for 25 years).... . 3. Did you stay at the hotel when you were in London?........ . How long had you been living there when Jane arrived?(for a fortnight)..... .4. Did they study French before they went to France?...... . How long had they been studying it before they went there?(for 5 years ).... 5. Did they work on their book last year?....... . How had they been working on it before they sent it to the publishing house?(for 2 years).... .