5. 在编译程序采用的优化方法中，_____ 是在循环语句范围内进行的。 ①合并已知常量 ②删除多余运算， ③删除归纳变量 ④强度削弱 ⑤代码外提 A. ①④ B. ①⑤ C. ①④⑤ D. ③④⑤ ...

1. 设文法G（S为其开始符号）产生式如下： d S→aSb|ab|ε 则G是一个LR（1）文法。 A. 错误 B. 正确 ...

19. 文法G[A]：A→ε A→aB B→Ab B→a是 A. 正规文法 B. 二型文法 C. 上下无关文法 D. 不确定 ...

9. Every profession or trade, every art, and every science has its technical vocabulary. Different occupations, however, differ widely in the character of their special vocabularies. In trades and handicrafts, and o...

4. According to the author, Americans' cultural blindness and linguistic ignorance will ________ . A. affect their image in the new era B. cut themselves off from the outside world C. limit their ro...

15. It can be seen from the passage that the expansion of America's elderly population ________. A. will provide good job opportunities in many areas B. will impose an unbearable burden on society C. may lead to nursing hom...

29. Before the conference begins, let’s take an _______ of the present situation. A. overall B. overview C. overture D. oversight ...

40. We were asked to ________ from smoking until the plane was airborne. A. resist B. restrain C. restrict D. refrain ...

10. The number of registered participants in this year's marathon was half _____. A. of last year's B. those of last year's C. of those of last year D. that of last year's ...

3. The professor can hardly find sufficient grounds _____ his argument in favor of the new theory. A. which to base on B. on which to base C. to base on which D. which to be based on ...