Vitamin D helps our bodies make a special chemical,and this special chemical,________,affects our brains,making us feel happy.
When she was awake, she found that she was lying on____seemed to be a piece of stone.
---Please tell Bruce he has won the first prize in the maths contest. ---_____He never did so well before.
I got up early this morning, but I ________ so because I was not on duty today.
It’s dangerous to have the fire _______ at home all night long.
The article is too long and should be _______ by half.