The old man smiled when he saw how pretty up to be during the past few years.
A. had his daughter grown
B. would his daughter grow
C. his daughter would grow
D. his daughter had grown
网友回答
A. had his daughter grown
B. would his daughter grow
C. his daughter would grow
(答案→)D. his daughter had grown
解析：宾语从句后面用陈述语气。另外，根据时间状语during the past few years可判断，应用完成时态。