S1:Crude oil obtained from the field is taken to a refinery for treatment

S6:Lubricating oils of various grades are obtained last of all

P:The gas that comes off later is condensed into paraffin

Q:This allows substances with different boiling points to be seperated

R:The first vapours to rise when cooled produce the finest petrol

S:The commonest form of treatment is heating

S1:On 5th October 1818,when young Lincoln was approaching his tenth year,his mother Nancy died of fever

S6:His total education at school comprised only about a year which he however managed to master reading,writing,spelling and some arithmetic

P:She was illiterate but she bought with her several books,among which were Pilgrim's progress,Sindbad the sailor,Robinson Crusoe and Aesop's fables

Q:Lincoln always acknowledged this moral and intellectual debt  to his step mother

R:The following year,his father married Sarah Bush Johnson,a widow with three children

S:These books provide Linclon with a mass of knowledge

S1:People very seldom have everything they want

S6:Our decisions indicate our scale of preferences and therefore our priorities

P:Usually we have to decide carefully how to spend our income

Q:They may all seem important,but their true importance can be measured by deciding which we are prepared to live without

R:When we exercise our choice,we do so according to personal scale of preferences

S:In this scale of preferences,essential commodities come first,then the kind of luxuries which help us to be comfortable, and finally those non-essentials which give us personal pleasure             

S1:When a lamb is born,its mother may die

S6:If a means of overcoming this natural tendency is found,lives of millions of lambs may be saved

P:Then there will always be both motherless lambs and sheep without lambs

Q:However,a sheep which has lost its lamb will not feed or look after a motherless lamb

R:At the same time,some new born lambs are too weak to live

S:This happens in large flocks where many sheep give birth to lambs at the same time

S1:The first thing you have to do is to speak with a strong foreign accent and speak broken english

S6:Half a dozen people will immediately overwhelm you with instructions

P:He will be interested in you becaues you are a foreigner and try to understand you and be ready to help you.

Q:He will not expect you to be polite and use elaborate grammatical phrases

R:Then every english person to whom to speak will at once know you are a foreigner and try to help you

S:If you shout,"Please,Charing cross?Which way?",you will have no difficulty

S1:The old man wanted to cross the road

S6:Holding him by the hand,the driver helped him to cross the road

P:The driver got off and came to him

Q:He was fed up and was about to return

R:Then a car stopped in front of him

S:He waited for a long time