According to the passage, we can expect a supernova to occur in our galaxy ______.
A. about twice each year
B. hundreds of times each century
C. about once every fifty years
D. about once every other century
查看答案
According to the passage a neutron star is ______.
A. a gaseous cloud containing heavy elements
B. an intermediate stage between an ordinary star and a supernova
C. the residue that is left by a supernova
D. the core of an ordinary star that houses the thermonuclear reactions
The author mentions all of the following as being involved in antigen-antibody immunological reactions EXCEPT the______.
A. synthesis of a protein
B. activation of complement in the bloodstream
C. destruction of antibodies
D. entrapment of antigens by macrophages
The author supports the theory of cell-mediated reactions primarily by ______.
A. pointing out a contradiction in the assumption leading to the antigen-antibody theory
B. explaining how cell mediation accounts for phenomena that the antigen-antibody theory cannot account for
C. revealing new data that scientists arguing for the antigen-antibody theory have continued to ignore
D. showing that the antigen-antibody theory fails to account for the breakup of antigens
The author most probably believes that the antigen-antibody theory of immunological reaction______.
A. is wrong
B. was accepted without evidence
C. is unverifiable
D. is a partial explanation
微信支付 
支付宝支付