At times, worrying is a normal, ________ response to a difficult event or situation --- a loved one being injured in an accident, for example.
I don't agree with your plan. You should never put your fortune ________ luck.
—What a pity that he missed his final shot and ended in a tie! —Yes, but he didn't lose it ________! It just wasn't his day.
The pregnant woman always sits in the nonsmoking area of restaurants to reduce her exposure ________ smoke.
My visit to your school is really an unforgettable experience, ________ I will treasure for ever.
________ giving a general introduction to computers, the course also provides practical operation.