【单选题】Newspapers and scientific journals are both______.
A.
suffering from revenue shrink
B.
operating under systematic reviews
C.
facing huge pressures to change
D.
moving in the direction favored by Shirky
【单选题】已知向量 a =(3,4), b =(2,-1) ,如果向量 a +x b 与 b 垂直,则x=( )
【单选题】The construction portfolio may be included as part of the ship ().
C.
builders documentation
【单选题】唯物主义和唯心主义在世界统一性问题上的根本分歧是( )
【单选题】已知向量 a =(3,4), b =(2,-1),如果向量 a +x b 与 b 垂直,则x的值为 [ ]