【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】阅读下文,回答题 The Chinese have used a method called acupuncture(针灸) to perform. operations for about 4,000 years without putting the patient to sleep. This involves placing flexible needles into certain pa...
【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 [ ]
【单选题】已知向量 a =(2,1), b =(x,-2)且 a + b 与2 a - b 平行,则x等于( )