【单选题】Which of the following supporting areas is not required for the setting of the emergency department ?.......................................................................... ( )
【单选题】已知 . F 1 = . i +2 . j +3 . k , . F 2 =-2 . i +3 . j - . k , . F 3 =3 . i -4 . j +5 . k ,其中 . i , . j , . k 为单位正交基底,若 F 1 , . F 2 , F 3 共同作用在一个物体上,使物体从点M 1 (1,-2,1)移到M 2 (3,1,2),则这三个合力所作的功为( )