"+"
I've been digging the garden since morning
she's already been waiting for me for ten minutes.
it has been raining for the whole day.
I have been doing my homework since 2 o'clock
Tom has been repairing his car for a couplr of hours
"-"
she hasn't been watching T.V. since morning
I haven't been doing my homework for an hour
they haven't been swimming since 3 o'clock
I haven't been studying for my exams for a month
Laura hasn't been sitting an exam for an hour
"?"
your hair are wet. have you been swimming?
Has it been snowing since morning?
has she been baking a cake for half an hour ?
have they been watching TV since morning?
Has she been writing an essay for the whole Sunday evening?