It was seven o;clock in the morning ____ he came back.It was really at seven o’clock ___ he came back from work this morning.

One can’t do extreme sports _________ he or she has had some training.

 You must observe and gather information like Nicolaus Copernicus ________ you want more career advancement opportunities. 

She treats the boy like that     she were his mother.

Humans are destroying nature day by day, ________, of course, will cause punishment sooner or later.