-----Hello, Jessica! What happened?----- I could not hear you clearly because my mobile phone could not receive a good ________.

I didn’t know it could do terrible ______to your heart and lungs or ______was more difficult for smoking couples to become pregnant.

At the conference, people of different _______ were given a chance to exchange theirs with each other. 

Dogs are our good friends as they can keep ______ with us when we are lonely．

---Where’s your father? ---At ____.