I__________ you somewhere before, but your name has escaped me_________.
He waited until it was dark ____ nobody could see him clearly.
Now there are many _____ in our company.
We should think of ways to stop the waste from the factory _____ our living environment.
As far as I know, this man ____ risk anything than lose the ring for his wife.
She locked her room _____ a thief would break into it.