I didn’t hear your call because I ______ to music at that time.

We won’t go to the park if it   ________ tomorrow.

I’m not sure if it _________tomorrow。If it __________ ,we won’t climb the South Hill. 

---How often ___________ the Olympics _____________? ---Every four years. 

_ How was your holiday last weekend? _Wonderful. I_______to the Great Wall with my parents.