-Is this kind of digital camera made of steel?-Yes, and it's widely used ______ taking photos.
Time seems ______ when we are playing computer games.
David often helps Sandy ___ her Maths, he also shares his school things ___ her.
My best friend Jack looks happy, and he always ________ a smile ________ his face.
She is ready to help people ________.
The _________ joke often makes the children.