19.Vitamin D helps our bodies make a special chemical, and this special chemical,________,affects our brains, making us feel happy.
__________ other students, Bill is more ___________ to the teachers.
This is the way ________ which he studies English.
. Everybody _________spend ___________ in bed.
__________ by the beauty of nature , the girl decided to spent another day on the farm.
You can eat food free in my restaurant _ _______ you like.