Without the air to hold some of the sun’s heat, the earth at night _______, too cold for us to live.[ ]

Tom didn’t go hiking with his classmates ________his illness.

wonder why he has been acting so strange these days.—Recent pressure at work may_____ his behavior. 

He’s never sung French songs before, has he—___________. It’s his second time to sing in French.

Professor Haley told me that he__________by many of his students at the railway station