He is running ________ the wind towards the east of the station ________ Tom running ________ the right.
Vitamin D helps our bodies make a special chemical,and this special chemical, ____ , affects our brains,making us feel happy.
We should be able to do the job for you quickly, ____you give us all the necessary information.
— Mrs.Smith,please teach me how to draw on the computer today. —Oh,no. ____.You have to get familiar with the keyboard first.
Overpopulation is a terrible threat to the human race.Yet it is probably ____ a threat to the human race than environmental destruction.
Ladies and gentlemen,welcome to my program.____ me this evening is Dr.Gray.