1. How long have you been making a cake? I have been making a cake for two hours already.
2. How long has yourfriend been drinking coffee? - Your friend has been drinking coffee for 20 minutes .
3. Have students been reading this text for thirty minutes? - Students have been reading this text for thirty minutes.
4. What has she been singing the whole evening? - She has been singing songs the whole evening.
5. Has John been preparing dinner since 3 o'clock? - John has been preparing dinner since 3 o'clock.