【单选题】设全集 U ={1,2,3,4},则集合 A ='{1,' 3},则C U A=( )
【单选题】听力原文:W: Have you finished your research report? M: Finished? It would take days. Q: What do we learn from the conversation? (7)
A.
The report is difficult.
B.
The report is very long.
C.
The report has been finished.
D.
The report will be finished in two days.
【单选题】设 ,若f(f(1))=1,则a=( )
【单选题】小儿何年龄起能形成兴奋性和抑制性条件反射:( )
【单选题】全年检修,抽检()%并按年检力矩进行紧固。如发现有一颗螺栓松动则整个节点的螺栓应全部紧固一遍
【单选题】设集合 A={2,3, a}, B={1,4}, 且A ∩B ={4 },则a = ( )