Use Present Perfect Continuous or Past Perfect Continuous 1. Why are you so dirty? I (play) football with my friends 2. How long ... you (learn) Arabic? 3. Kate was very tired, she (do) her room since afternoon / 4. We (wait) for train for for half an hour

1. i have been playing

2. have you been learling

3. had been doing

4. we have been waiting

1) have been playing (из контекста ясно, что действие только закончилось и и оставило своеобразный "след", что и объясняет положение вещей в момент речи

2) have you been learning (продолжительность действия, период времени)

3) had been doing (предшествование, те два действия, где одно произошло первее, другое действие - позже)

4) have been waiting (действие выполняется уже какой-то период времени т. е for-в течение)