It can be concluded from the first paragraph.that__________ .
A.the author is against eating frogs
B.taste is illogical and inarguable
C.some types of frogs are poisonous
D.taste is influenced by many factors
设求A',B',A'+B',A'B',B'A',(A')2。
A.∪B={0,1}
B.∪B={-1,0,1}
C.∪B={-1,1}
D.∪B={-1,0}