The important thing is that this is a major breakthrough. “breakthrough” here means an important development or achievement.

It should be apparent that little or nothing is gained by opening a drain at the same time as or after admitting steamThe above sentence probably means （）.

Project（71）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．

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．

● Project（71）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.（71）

 ______ 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.

Scientists say it may be five or six years _____ this medicine is tested on human beings.

Is this（）longer or shorter?

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

A salvor may be（）the whole or part of the payment due under Salvage Convention to the extent that the salvage operations have become necessary or more difficult because of fault or neglect on his part or if the salvor has been guilty of fraud or other dishonest conduct.

A mark or place at which a vessel comes under obligatory entry，transit，or escort procedure is know as（）.

（）refers to a word or expression that is prohibited by the “polite” society from general use.