because的话,2种情况,单独because,后面加从句,就是
Tom cann't go out to play,because he has a lot of homework to do.
或者是because of,后面加名词短语,Tom cann't go out to play because of a lot of unfinished homework.
"With the lights off,we could not go on with the work."-可以改成,
Because of power cut/lacking the lights,we could not go on with the work.
We could not go on with the work,because the lights were off.