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

You’d better ask Mr Wang for help when _______ problems.—I see, but I’m not sure when _______ time.

The villagers went out to the mountain__________ the missing child.

__________ difficult the task may be, we will try our best to complete it in time.

l professors from Peking University came tovisit our school, to my surprise, one of ________ was my aunt.