As young adults, it is our_____ to try our best to deal with each challenge in our education with the help of our teacher. 

 —Excuse me, is this ________ new pencil sharpener?  —Yes, it’s ________. He bought it just now.

--Are you sure Mr Bush is at home? --Let’s try ringing the       _.

There is some       and potatoes in the fridge.

Those are _________.