8岁男孩,疝内容物可达阴囊处,疝块回纳后,压内环,增加腹压不再出现。诊断应考虑为
A.腹股沟斜疝
B.脐疝
C.股疝
D.白线疝
E.腹股沟直疝
参考答案:A
______ the beginning of the 19th century did scientists know that all matter is made up of atoms.[ ]
A. At
B. By
C. Up to
D. Not until
关于x的方程x(a+2)=2x+1(a≠0)的解是______.