[la aurora]

Remember:

voiced consonant sounds unvoiced when:

- it's the last letter of the word (for example хлеб /bread/ sounds like хлеп. But if this word is a part of the sentence and next word starts with vocal or voiced consonant)
- it's followed by unvoiced consonant (4 example завтра /tomorrow/ sounds like зафтра as 'т' is unvoiced and it influents the previous voiced letter 'в' changing it to unvoiced 'ф')

(so voiced sound stayes voiced if it's followed by vocal or another voiced consonant)

But sometimes it's vice versa - unvoiced consonant suddenly sounds voiced. It happens when:

- the letter is followed by voiced consonant. No matter if it happens in one word, or it's just the last letter of the word and next word starts with the voiced consonant. In both cases unvoced changes to voiced. (4 example футбол sounds like фудбол. наш дом sounds like наж дом)

*watches some students standing up and leaving the classroom*

Hey, guys! Come back!!! It's not as difficult as it seems. Just 6 pairs to remember...
http://www.geocities.com/nrg2002ru/consonants2.mp3