楼上的例子明显是错误的.
英语的强调句有个特点,就是去掉it was 和 that 再把剩下的连起来,剩下的部分一定能够组成一个完整的句子,所以,楼上英语强调句：It was 10 o'clock that we arrived at the airport. 要改成It was at10 o'clock that we arrived at the airport.时间状语从句和楼上一样. 如果是单选,就是去掉it was 和 that 再把剩下的连起来,如果完整,就是强调句,选that,不是,就是when