单项选择题The period ranging from 1865 to 1914 has been referred to as ______ in the literary history of the United States.
单项选择题You ______ buy a gift, but you can if you want to.
单项选择题______ before you leave the lab.
单项选择题I was impressed______the efficiency of the work done in the company.
单项选择题The idea came to me when I ______ with him.