A:C14H18O5
B:C14H16O4
C:C14H22O3
D:C14H10O3
A. I want to buy some toys.
B. Go straight down this street. Turn left at the traffic lights.
C. Sure.
D. He is flying a kite.
E. They played basketball.
为使教室内的学生免受环境噪声的干扰,下列哪种方法是最合理的?( )