—Mary, could you tell me if your mother ________ our school sports meeting tomorrow? —I think she will come to school if she _________ free.
I’m sorry I’m late again________ the heavy rain.
If it_________ tomorrow, I’ll go birdwatching with my father. -----That’s a good idea.
Not everyone knows_____they want to be.
Science is _____ difficult for some students ____ learn, so many of them don’t like it.
---What are you doing? ---I’m_____my English book.