To turn off my cell phone before going to bed seems to be a rule .
So many uses have been discovered for this wood ____ the supply of white pine is becoming smaller and smaller.
The truth, Sir, is that the old man____ across the street when my car hit him.
I wrote to my parents once a week,____ I was too busy with my teaching work.
However, at times this balance in nature is disturbed, ____ a number of possibly unforeseen effects.
--- He has to finish the experiment today. He must be in the lab,____?---That s quite possible.