Seeing the chemical ________ to the sunlight, Mr. Lee warned the workers to be careful when dealing with it.
The mid-term exam is to be held ___ the end of this month.
I’ll be free ___ seven o’clock.
We offered him our congratulations ___ his passing the college entrance exams.
In the dark street, there wasn’t a single person ___ she could turn for help.
___ this book and tell me what you think of it.