1 We know how long he has been working
2 I remember how long she has been teaching English
3 you know how long they have been playing hockey
4 she remembers how long you have been waiting for it
5 he knows how long we have been building that house
6 they remember how long I have been traveling
7 I like how long she has been doing her homework
8 he understands how long his friend has been cooking
9 you see I have just received this email.
10 he has already done his homework
11 this is the worst film I have ever seen
12 that is the most beautiful place you have ever visited
13 it's the most expensive food she has ever eaten