1. ____ that caused him to serve dinner an hour later than usual.
A. It was we being late B. It was our being late
C. It was we were too late D. It was because we were late
【陷阱】此题容易误选D，认为强调的是原因状语从句 because we were late.
【分析】但实际上，此题的答案为B，强调的是句子主语 our being late，此题若还原成非强调句，即为：
Our being late caused him to serve dinner an hour later than usual.
