The expressions they use might whom they are speaking to or how well they know each other.
We will go to Tian’anmen Square to watch the raising of national flag if it ________ tomorrow.
— How often do I need to feed the dog? — It ________ food every day, or it will be hungry.
My friend and I are interested in drawing, but ________ of us is good at it.
— Is Jack in the next room? — Well, it’s hard to say. But I heard him ________ loudly when I passed by just now.
— Dick, ________ I use your e-dictionary? — Yes, sure. ________ you give it to David after you use it?