过圆水准器零点的球面法线称为:()
A.水准管轴
B.铅垂线
C.圆水准器轴
D.水平线
参考答案:C
下列依次填入横线处的词语,恰当的一组是( )。 与常规的计算机相比,生物计算机具有密集度高的突出优点。______用DNA分子制成生物电子元件,将比硅芯片上的电子元件要小得多,______项式可小到几十亿分之一米。______,生物芯片本身具有天然独特的立体化结构,其密度要比平面型硅集成电路高10万倍。
A.由于 甚至 所以B.只是 也许 可见C.如果 甚至 而且D.虽然 也许 然而
Facts about Aging
Which of the following statements is true of elderly people A. They are interested in joining close family members.B. They are enthusiastic for making new friends.C. Many of them suffer from serious illnesses.D. Many of them live in poverty.