Experts hby passive smoking.

The boy was sitting ___ his mother, ___ his back ___the door[ ]

I am ________ endless examinations.— Cheer up, David.Keep on until the college entrance examination ends. [ ]

__________ attracts movie goers in the film Avatar is its vivid three-dimension effect (三维效果) , grand war scenes and touching love story

Dogs are kept to ______ the houses from thieves at night.