侧位胸片上，右叶中央型肺癌伴有右中叶、右下叶不张时，形成的征象称为()

A．饼征

B．双翼征

C．膈上半月征

D．龟背征

E．膈角移位征

While most recent attention in the AI field has been focused on expert system software, AI (66) has also seen dramatic advances. Activity in the past years was characterized by new low-cost, powerful Lisp machines, the introduction of AI workstations, Lisp compilers becoming available for all major professional and engineering workstations, and the personal computer emerging as a (67) . tool for expert system development. The next few years will see this technology evolves further.

Because the (68) of an AI computer represents a sizable investment, companies should carefully (69) all options that are available as well as have a good idea of what the next generation of systems will offer in order to (70) the optimum system. This publication provides the information necessary to gain this understanding.

（69）是（）

A. choice

B. read

C. important

D. software

E. hardware

F. significant

G. emergence

H. survey

I. purchase

J. select