新概念三 Lesson49 The Ideal Servant 里的句子:
The guests had, of course, realized this from the moment Bessie opened the door for them and, long before the final catastrophe, had had a difficult time trying to conceal their amusement.
谢谢了!!
非常感谢 ,还想问一下,那两个连在一起的had,怎么解释 ,是什么时态?