By six o'clock on Sunday I had already learned all the words
К шести часам в воскресенье я уже выучил все слова.
By six o'clock on Sunday I hadn't learned all the words yet.
By what time on Sunday had I learned all the words?
By six o'clock on Sunday you had already learned all the words, had't you?
She had leftby the 1st of June - Она уехала (еще) допервогоиюня.
She hadn't left by the 1st of June yet.
Had she left by the 1st of June?
She had left by the 1st of June, hadn't she?
She had written only two letters by noon
К полудню она написала только 2 письма.
She hadn't written letters by noon.
She hadn't written letters by noon, had she?
How many letters had she written by noon?
We hadn't finished our work by her returning.