What is an UFO? A: It is an Unknown Flying Object. B: It is an Unidentified Flying Object. C: It is an Unknown Flowing Object. D: It is an Unidentified Flowing Object.

中国大学MOOC: In the USA in 1967, a man reported ________ UFO (unidentified flying object).

In the USA in 1967, a man reported ________ UFO (unidentified flying object). A: X B: a C: an D: the

Who is the narrator of "Everyday Use"? ____ A: Dee B: the<br/>Mother C: Maggie D: Unidentified

People use the word "unidentified" to describe the reported flying objects .because what these objects are is still unknown.

Seeing an unidentified man walking into the plant, the doorman stopped him. A: unrecognized B: unimportant C: impolite D: unfriendly

The tool tip of the external turning tool is installed higher than the workpiece rotation axis, the working rake Angle of turning tool is （ ）than that of marked rake angle A: lager B: smaller C: equal to D: unidentified

It is very important that we should not in protecting computer system. A: display our passwords for everyone to see B: open unidentified files C: leave computer terminals on while we are away from our desks D: all of the above

In the case of a family in Vietnam, ______. A: WHO said all of the members contracted the bird flu B: experts think it's possibly caused by the spread of bird flu C: three of them fell ill due to a serious unidentified disease D: the sisters caught a disease after tests were done on them