19.Vitamin D helps our bodies make a special chemical, and this special chemical,________,affects our brains, making us feel happy.
When we went past her house, we heard her ____ in her room.
To get there in time, they came ______ all the way.
Finding her car stolen, ___________.
In doing scientific experiments one must be _______ careful with the instruments.
She _______ to the waiter whose language isn’t ______ hers to bring some more coffee.