问题
选择题
Mr. Smith is busy these days ________ a new book on how to develop a child’s reading skill.
A．working out
B．working on
C．working for
D．working with
答案
答案：B
本题的含义是史密斯先生这些天正忙于写一本有关培养儿童阅读技能的书，work on表示忙于或从事的意思，符合本题含义，故本题选B。