【正文】 signed li ving areas, cars ar e unnecesary. At f ir st , t he gover nment had gr eat dif fi cul ty i n pers uadi ng peopl e to l eave Ri o and t o set tl e in Br asi li a. Si nce 1960, however, t he popul at ion has been gr owing al l the ti me. Bras il ia has quickly establi shed i tself as the capital of the countr y. The i dea t o have the capital moved so far i nl and wil l have a gr e at ef fect on the f ut ure of Br azi l. Leson91 Three men i n a basket 三人同籃 A pil ot not iced a bal loon whi ch seemed t o be making f or a Royal Ai r Force Stat ion nearby. He inf ormed t he stati on at once, but no one there was abl e to explai n the m yst er y. The of fi cer i n t he contr ol tower was ver y angry when he heard the news, because baloons can be a great danger to ai rcraf t. He said t hat someone might by spyi ng on the st at ion and t he pi lot was order ed to keep tr ack of t he st range object. The pil ot m anaged to ci rcl e the bal oon for som e ti me. He coul d make out thr e men in a basket under i t and one of t hem was holding fi el dglasses. When t he bal loon was over t he st ati on, t he pi lot saw one of the m en t aki ng phot ogr aphs. Soon aft er wards, the bal oon began to descend and i t landed near an ai rf iel d. The poli ce were cal ed in, but they coul d not ar rest anyone, f or the basket cont ai ned two Members of Parl iament and the Comm anding Of f icer of t he stati on! As the Comm anding Of icer expl ai ned later , one half of t he st at ion di d not know what t he other hal f was! Leson92 Aski ng for t rouble 自找麻 煩 It m ust have been about t wo i n the m or ning when I r eturned home. I tr ied t o wake up my wif e by r inging t he door bel , but she was fast asleep, so I got a l adder fr om t he shed i n the gar den, put i t agai nst the wal l, and began cli mbi ng towards t he bedr oom wi ndow. I was alm ost t her e when a sar cast ic voice below sai d, 39。t t hi nk the wi ndows need cl eaning at t hi s ti me of t he ni ght.39。I enjoy cl eani ng windows at night. 39。 answered t he pol iceman in the same tone. 39。s busy wor king, but woul d you mind i ng wi th me to t he Wel l , I 39。 I sai d. 39。ve f or got t en m y key. He cal l ed. 39。 I shout ed. 39。倒立擺系統(tǒng)存在嚴重的不確定性，一方面是系統(tǒng)的參數(shù)的不確定性，一方面是系統(tǒng)的受到不確定因素的干擾。在多種控制理論與方法的研究和應(yīng)用中，特別是在工程中，存 在一種可行性的實驗問題，將其理論和方法得到有效的驗證，倒立擺系統(tǒng)可以此提供一個從控制理論通過實踐的橋梁。因此，從控制這個角度上講，對倒立擺的研究在理論和方法論上均有著深遠意義。隨著非線性科學的發(fā)展，以前的采用線性化方法來描述非線性的性質(zhì)，固然無可非議，但這種方法是很有局限性，非線性的一些本質(zhì)特征往往不是用線性的方法所能體現(xiàn)的。在倒立擺系統(tǒng)中含有極其豐富和 復(fù)雜的動力學行為，如分叉、分形和混沌動力學，這方面的問題也值得去探討和研究。實際中可以通過線性化得到系統(tǒng)Her e and t here: they had just di scovered t hat a pr isoner had escaped. At t hat mom ent , a large bl ack car wit h f our of fi cer s inside i t, stopped at t he camp gat es. The off icers got out and t he pri soner st ood to at tenti on and salut ed as t hey passed. When t hey had gone, the dri ver of t he car came t owar ds him. The man obviously want ed to t alk. He was r at her el der ly wi t h grey hair and clear blue eyes. The pri soner felt sorr y f or hi m, but t her e was nothi ng el se he coul d do. As the man came near, the pr isoner knocked hi m t o t he gr ound wit h a shar p bl ow. Then, jumpi ng into the car, he drove of f as quickly as he could. ？ Fishermen and sail or s som etim es cl ai m to have sen m onster s in t he sea. Though people have oft en laughed at stor ies tol d by s eamen, it i s now known that many of these 39。 which have at t imes been si ghted are si mply st range fi sh. Occasi onal y, unusual creatur es ar e washed t o t he shore, but they are r arely caught out at sea. Some ti me ago, however, a pecul iar fi sh was caught near Madagascar . A smal l f i shing boat was car r ied mi les out to sea by the power ful fi sh as it pulled on the li ne. Reali zing t hat thi s was no or di nar y f ish, t he fi sher man made ever y ef ort not to damage i t i n any way. When it was event ualy brought t o shor e, i t was found t o be over t hi r teen feet long. I t had a head l ike a hor se, big bl ue eyes, shini ng si lver ski n, and a br ight red t ail , t he fi sh, whi ch has since been sent to a museum where i t is being examined by a scienti st , is cal ed an oar fi sh. Such creature s have rar el y been seen ali ve by man as they l ive at a dept h of si x hundr ed f et. Lesson83 Af ter the el ecti ons 大選之后 The f ormer Pr ime Mini st er, Went wort h Lane, was defeated i n the r ecent elect ions. He is now reti ri ng f rom pol it ical lif e and has gone abroad. My f r iend, Cr awley, has al ways been a f anati cal opponent of Lane39。s house. When he asked i f Lane l ived ther e, t he pol iceman on duty t old hi m t ha t si nce hi s def eat , t he exPr ime Mini st er had gone abroad. On the f oll owi ng day, Cr awley went t o the house again. The same policema n was j ust walki ng slowly past the entr ance, when Crawl ey asked the same quest ion. Though a lit tl e suspici ous t his t ime, the pol i cem an gave him the same answer . The day af ter , Cr awl ey went t o the house once m or e and asked exact ly t he same questi on. This t im e, t he pol iceman l ost his t em per .39。 he shout ed, Lane was def eat ed in the electi ons. He has reti r ed f r om poli ti cal li f e and gone t o li ve 39。 answer ed Cr awl ey,39。 Lesson84 On st ri ke 罷工 Busmen have decided to go on str ike next week. The st ri ke is due t o begi n on Tuesday. No one knows how long i t wil l last . The busmen have stated t hat t he st ri ke wil l cont inue unt il gener al agr em ent is r eached about pay and worki ng condi tions. Most pe ople beli eve that he str ike wi l last for at least a week. Many owners of pri vat e cars are goi ng to of fer 39。 t o peopl e on t hei r way to wor k. This wi l r el ieve pressur e on t he tr ai ns to some extent. Meanwhi le, a num ber of universit y student s have vol unt eer ed to dr ive buses whi le the str ike l asts. Al l the yo