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举一反三
【多选题】食管痉挛的叙述正确的是（）。
A.
食管造影的X线表现可多样
B.
一般在食管半充盈情况时出现
C.
食管可呈螺旋状、波浪形或串珠状较为对称的狭窄
D.
表现为间隔1~2cm的4~5个较深的环形收缩
E.
狭窄食管僵硬，狭窄近端扩张
【单选题】Defective Genes and Human Health Each of us carries about half a dozen defective(有缺点的) genes. We remain blissfully(快乐地) unaware of this fact unless we, or one of our close relatives, are amongst the m...
A.
Genetically engineered proteins are better than blood products in treating hemophilia.
B.
Only those who suffer from a genetic disease carry about half a dozen defective genes.
C.
The Y chromosome males have are from their fathers.
D.
Whether a defensive gene produces ill effects has something to do with the environment in which the gene operates.