问题
选择题
The kid was making noise just to attract attention. Let him be!
A．in addition
B．in vain
C．on average
D．on purpose
答案
答案：D
考查短语辨析。in addition此外，in vain白费力，on average按平均计算，on purpose故意的，根据句意孩子们故意发出噪音仅仅是引起注意。故选D。