最易引起阑尾穿孔的是（）

A.急性单纯性阑尾炎

B.急性坏疽性阑尾炎

C.慢性阑尾炎

D.亚急性阑尾炎

E.慢性阑尾炎急性发作

Software engineering is the science and art of specifying, designing, implementing, and (66) with economy, timeliness and elegance, programs, (67) and operating procedures whereby computers can be made useful to humanity.

This definition implicitly sets (68) the basic goal of software engineering research and development: The basic goal of software engineering is to facilitate specification, design, implementation and evolution of programs, documentation and operating (69) which are useful to humanity in an economic, (70) and elegant manner (using the appropriate science and art).

（69）处填（）。

A．proceeding

B．procedures

C．progress

D．systems