They _____ the problem since one o clock. 
have been discussing
have being discuss
have being discussed

The candle _____ for two hours. 
has being burn
has being burned
has been burning

____ the secretary _____ out the documents?
Has, being print
Has, being printed
Has. been printing

The researcher _____ the territory since last December. 
has being explor 
has been exploring
has being explored

They have never been to Australia. 
How often have they been to Australia? 
Have they ever been to Australia? 
Often have they been to Australia? 

They _____ a new gadget.
have being inventen
have been inventing
have been invented

How long ____ the dog been _____ around?
have, been running
has, running
has, been running

Ben _____ that blue shirt since Friday. 
has being wear
has been wearing
has being wearing

Lucy _____ on the task.
has not been concentrating
has being not concentrated
has been not concentrated

How long _____ at the door?
you have been knocking
have you being knocked
have you been knocking