C is sometimes referred to as a ’high -level (66) language’. Some people think that’s an insult, but it’s actually a deliberate and significant aspect of the language. If you have (67) in assembly language, youll probably find C very natural and comfortable (although if you continue to focus too heavily on machine - level details, youll probably end up with unnecessarily non- portable programs). If you havent programmed in assembly language, you may be frustrated by C ’s lack of certain higher - level features. In either case, you should understand why C was de- signed this way: so that seemingly - simple constructions expressed in C would not expand to arbitrarily expensive ( in time or (68) ) machine language constructions when (69) . If you write a C program simply and succinctly, it is likely to result in a succinct, efficient machine language executable. If you find that the (70) resulting from a C program is not efficient, it’s probably because of something silly you did, not because of something the compiler did behind your back which you have no control over. In any case, there’s no point in complaining about C’s low - level flavor: C is what it is.

A. assembly B. combination C. grouping D. compounding

患者男性，30岁，长期居住在东北的缺硒山，区。近3年出现心悸、气短伴双下肢水肿。体格检查发现心界向左下扩大，心音低钝，心律失常，肝大。首先应考虑（）

A.风湿性心脏病

B.克山病

C.病毒性心肌炎

D.冠状动脉粥样硬化性心脏病

E.先天性心脏病