问题补充：
---How long will Tom stay here? ---.
A. One and a half year
B. A year and a half
C. One and a half year
D. both A and B
答案：
A. One and a half year
B. A year and a half
C. One and a half year
(答案→)D. both A and B
解析：一年半可说成:one and a half years 或 a year and a half
