16. This is the first time I have ever met such a famous person -> I’ve _____________________________________________________ 17. How long is it since they bought the house? -> When __________________________________________________ 18. I have never read such an interesting novel -> This is __________________________________________________ 19. After he had worked hard many years, he retired -> Before ___________________________________________________ 20. When did you collect stamps? -> How long ________________________________________________ Làm giúp e với ạ, e quên hết công thức l9 luôn rùi🥲 ai có lòng thì ghi công thức với chút xíu cách làm với ạ. Em cảm ơn nhiều nhiều lắm ạa🥺💕