某钢筋混凝土简支梁如图2-1所示。纵向钢筋采用HRB335级钢筋(

)，该梁计算跨度l₀=7200mm，跨中计算所需的纵向受拉钢筋为4

25。

试问，该简支梁支座区上部纵向构造钢筋自支座边缘向跨内伸出的最小长度l_c(mm)，选用下列何项数值最为恰当

For each blank, choose the best answer from the four choices and write down on the answer sheet.

(66) is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.

(67) is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.

(68) is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable.

(69) is a device used to connect two separate network that use different communication protocol.

(70) is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.

67（）

A．RTP

B．RTTP

C．FTP

D．NNTP