（）is a computer technology that headsets,sometimes in combination with physical spaces or multi-projected environments,to generate realisitic images,sounds and other sensations that simulate a user’s physical presence in a virtual or imaginary environment.

The last sentence“And everyone knows what happens next”implies that in such cases ．

Clouds that form as small white flakes or scaly globular masses covering either small or large portions of the sky are（）.

Clouds that form as small white flakes or scaly globular masses covering either small or large portions of the sky are（）.

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（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）

外语导游人员要精通一门外语外，还要基本掌握一门第二外语，这是（）导游的要求。

（）外语导游员要求熟练掌握一门外语，初步掌握一门第二外语。

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（）.

By saying “While it’s true that ..., be they scientific or artistic” (Lines 1-3, Para.5), the author means that _____.