Standard English is the variety of English which is usually used in print and which is normally taught in schools and to non-native speakers learning the language. It is also the variety which is normally (1) by educated people and used in news broadcasts and other (2) situations. The difference between standard and nonstandard, it should be noted, has (3) in principle to do with differences between formal and colloquial (4) ; standard English has colloquial as well as formal variants.

(5) , the standard variety of English is based on the London (6) of English that developed after the Norman Conquest resulted in the removal of the Court from Winchester to London. This dialect became the one (7) by the educated, and it was developed and promoted (8) a model, or norm, for wider and wider segments of society. It was also the (9) that was carried overseas, but not one unaffected by such export. Today, (10) English is arranged to the extent that tile grammar and vocabulary of English are (11) the same everywhere in the world where English is used; (12) among local standards is really quite minor, (13) the Singapore, South Africa, and Irish varieties are really very (14) different from one another so far as grammar and vocabulary are (15) .Indeed, Standard English is so powerful that it exerts a tremendous (16) on all local varieties, to the extent that many of long-established dialects of England have (17) much of their vigor and there is considerable pressure on them to be (18) . This latter situation is not unique (19) English: it is also true in other countries where processes of standardization are (20) .But it sometimes creates problems for speakers who try to strike some kind of compromise between local norms and national, even supranational ones.

17（）

A.lost

B.gained

C.missed

D.got

女性，56岁。昨日吃不洁水果，夜间出现发热、腹痛、腹泻，大便有脓血，量少，每日10余次，伴里急后重。体检：体温39．5℃，血压正常，神志清，心肺无异常，左下腹有压痛，无反跳痛，血白细胞18×10⁹／L，N0．85，大便检红细胞（++），脓细胞（+++），该型菌痢的发病机制最重要的是（）

A.痢疾杆菌毒素对结肠粘膜的直接损害

B.具有侵袭力的菌株进入结肠粘膜固有层，并在其中繁殖引起炎症与溃疡

C.痢疾杆菌大量繁殖引起病情严重

D.结肠急性弥漫性纤维蛋白渗出性炎症，形成溃疡

E.特异性体质对细菌毒素产生强烈过敏反应