——________do you go to the dentist?——Let me see, twice a year, maybe.
The white watch is _____ one of all my favorites.
---Did you notice someone enter the classroom just now?---Sorry, I didn’t. I _____ my lessons at that time.
_____ this cake, you’ll need 2 eggs, 175g sugar and 175g flour.
This is my book. _____ is over near the window.
He will arrive in Shanghai _____ three hours. Let’s go to meet him.