美国在科索沃战场上投下了至少10吨贫铀弹,贫铀弹的主要成分是低放射性的238U,它与制造原子弹的235U属于
A.同位素
B.同一物质
C.同分异构体
D.同素异形体
答案:A
It has been proved_______eating vegetables in childhood helps to protect you against serious
illnesses in later life.[ ]
A. if
B. because
C. when
D. that
下列不属于细菌特殊结构的是()
A.荚膜
B.质粒
C.鞭毛
D.菌毛
E.芽胞