I had no ______of who I was or what I was going to be.

The lower-level classes （known as subclasses or derived classes） （ ） state and behavior from the higher-level class （known as a super class or base class）.

Damage to cargo caused by fumes or vapor from liquids,gases, or solids is known as（）.

Either he or I ______to the airport.

—Do you learn Russian or French?—I learn _____.

—Do you learn Russian or French?—I learn ______.

Project ______is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

 ______ twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city.

It will be a relief over the death of a friend or a relative if the friend or relative dies from ______.

I think you should end it ______ it is too late, or you will be sorry for it.

Damage to cargo caused by fumes or vapors from liquids，gases，or solids is known as（）.