题目

阅读理解 There are many different places to eat in Switzerland. There are some fast-food restaurants, self-service restaurants and family restaurants. There are also some nice and expensive restaurants. Choosing where to eat is an experience. Food is more expensive in Switzerland than that in most of other countries in Europe. It is much more expensive than in the USA. In Switzerland if you go to a fast-food restaurant, you may easily spend up to 10 CHF (瑞士法郎) for a hamburger, a soft drink and cup of coffee. In a family restaurant, a meal usually costs you between 15 CHF and 50 CHOnly when I left for America ____________ how much I missed my parents. A. I realized        B. did I realize         C. I had realized    D. had I realized