I. 单项选择:(共50题;满分50分;每小题1分)
从A、B、C、D四个选项中,选出可以填入空白处的最佳答案,并在答题卡上将该项涂黑。
1. --- I serve three meals every day and do almost everything for him, but he still lets me down.
--- I’m afraid that’s ______ you are mistaken.
A.how B. where C. what D. in which