Vitamin D helps our bodies make a special chemical, and this special chemical, _______, affects our brains, making us feel happy.
34.Her fluency in English gave her an edge_______ other girls when she applied for the job.
33._________ in some rural schools that the teacher is even unable to walk through the rows of desks.
32.World leaders at the G20 summit conference in London decided to_______$1.1trillion(万亿) to supporting world economic growth and trade.
30.When you finish your work, don’t forget to put the tools back where they ________.
29.The police tried to get some clues from the suspect, but he remained________