【单选题】生物体内的蛋白质千差万别,即使像催产素、牛加压素、血管舒张素等由相同数量的氨基酸构成的蛋白质,生理功能也差异性很大。其原因不可能是( )
【单选题】有两个关系R和S,分别含有15个和10各元组,则在R∪S,R-S,R∩S中不可能出现的元组情况是:
【单选题】大量使用下列哪项利尿剂可能产生低渗性脱水
【单选题】听力原文:Sara: Now, let me just see. Yes, it certainly is swollen and rather inflamed. Sally: And, it seems to be going rather blue, doesn't it? Sam: Mm. Yes. Well, it could, of course, be a simple sprain...
【单选题】Passer-by: Is there a taxi stand on this street? Local resident: Let me see. Oh, yes, ______. Passer-by: Oh yes, I see it.
A.
it's not far from here
B.
you can see it from here
C.
there's one in front of the bank
D.
go to the bank to find it
【单选题】● 有两个关系R和S,分别包含15个元组和10个元组,则在R∪S,R∩S,R-S不能出现的元组数目情况是( )。( )