【正文】 hy. It i s onl y when the di sease has progressed to AIDS that a person begi ns to l ok si ck. Onl y hom osexual s get AIDS. WRON G. Anyone who has sex with a person i nfected wi th H IV/AIDS ri sks getti ng the vi rus. Women are sli ghtly m ore li kel y to be e infected than m en. If you hug, touch or ki s som eone with AIDS or vi si t them i n thei r hom e, you wil l get H IV/AIDS. WRON G. You can only get the disease from bl ood or sexual fl ui d. Unfortunatel y, peopl e wi th HIV som etim es l ose thei r friends because of prejudi ce. Many peopl e are afrai d that they wi l get H IV/AIDS from those i nfected wi th H IV/AIDS. For the sam e reason, som e AIDS pati ents cannot fi nd anyone to l ook after them when they are si ck. You can get H IV/AIDS from m osqui toes. WRON G. There i s no evi dence of thi s. Uni t 4 TH E EARTH IS BECO MIN G WARMER BUT DO ES IT MATTER? Duri ng the 20th century the tem perature of the earth rose about one degree Fahrenhei t. That probabl y does not seem m uch to you or m e, but i t i s a rapi d i ncrease when pared to other natural changes. So how has this e about and does i t m atter? Earth Care?s Sophi e Arm strong expl ores these questi ons. There i s no doubt that the earth i s be i ng warm er (see Graph 1) and that is i t hum an acti vi ty that has caused thi s gl obal warmi ng rather than a random but natural phenom enon. Al l sci enti sts subscri be to the vi ew that the i ncrease i n the earth?s tem perature i s due to the burni ng of fosil fuel s li ke coal , natural gas and oil to produce energy. Som e byproducts of thi s proces are cal ed “greenhouse” gases, the m ost im portant one of whi ch i s carbon di oxi de. Dr Jani ce Foster expl ai ns: “There i s a natural phenom enon that sci enti sts cal the ?greenhouse effect?. Thi s i s when sm al l am ounts of gases in the atm osphere, li ke carbon dioxi de, m ethane and water vapor, trap heat from the sun and therefore warm the earth. Wi thout the ?greenhouse effect?, the earth woul d be about thi rtythree degrees Cel sius cool er than i t i s. So, we need those gases. The probl em begi ns when we add huge quanti ti es of extra carbon di oxi de i nto the atm osphere. It m eans that m ore heat energy tends to be trapped i n the atmosphere causi ng the gl obal tem perature to go up. ” We know that the l evel s of carbon di oxi de have i ncreased greatly over the l ast 100 to 150 years. It was a sci enti st cal l ed Charl es Keeli ng, who m ade accurate measurem ents of the am ount of carbon di oxi de i n the atm osphere from 1957 to 1997. H e found that between these years the carbon di oxi de in the atm osphere went up from around 315 parts to around 370 parts per m il i on (see Graph 2). Al l sci enti sts accept thi s data. They al so agree that it i s the burning of m ore and m ore fossil fuels that has resulted i n thi s increase in carbon di oxi de. So how hi gh wi l the tem perature increase go? Dr Jani ce Foster says that over the next 100 years the am ount of warmi ng coul d be as l ow as 1 to 1. 5 degrees Celsi us, but i t coul d be as hi gh as 5 degrees. H owever, the atti tudes of sci entists towards thi s ri se are pl etel y di fferent. O n the one hand, Dr Foster thi nks that the t rend whi ch i ncreases the tem perature by 5 degrees woul d be a catastrophe. She says, “We can?t predict the cl im ate wel l enough to know what to expect, but it coul d be very seri ous.” O thers who agree with her thi nk there may be a ri se of several m etres in the sea l evel, or predi ct severe storm s, fl oods, droughts, fami nes, the spread of diseases and the di sapearance of speci es. O n the other hand, there are those, li ke Gee H am bl ey, who are opposed to thi s vi ew and bel i eve that we shoul d not worry about hi gh l evel s of carbon di oxi de i n the ai r. They predi ct that any warm i ng will be mi l d with few bad environm ental consequences. In fact, H am bl ey states, ” More carbon di oxi de i s actual l y a positi ve thi ng. It wil l m ake pl ants grow qui cker。 crops wil l produce m ore。 ARE YOU AT RISK? H IV i s a vi rus. A virus i s a very smal l i vi ng thing that causes di sease. There are many di fferent vi ruses, for exam pl e, the fl u vi rus or the SARS vi rus. H IV weakens a person?s imm une system。 crops wil l produce m ore。 i n fact, do anythi ng to keep your m i nd and especi al l y your hands busy. Rel ax. If you start to feel nervous or stressed, do not reach for a ci garette. Try som e deep breathi ng i nstead. Do som e rel axati on exerci ses every tim e you fel stresed. Get hel p if you need it. Arrange to stop sm oking wi th a fri end so you can tal k about your probl em s, or joi n a stopsm oki ng group. If you feel desperate, you mi ght li e to tal k to a doctor or chemi st about som ethi ng to hel p you, l i ke ni coti ne chewi ng gum . Keep tryi ng. Do not be di sappoi nted if you have to try several ti m es before you fi nal l y stop sm oki ng. If you weaken and have a ci garete, do not feel asham ed. Just try agai n. You wi l succeed eventual y. H IV/AIDS。 i n fact, do anythi ng to keep your mi nd and especial y your hands busy. Rel ax. If you start to feel nervous or stressed, do not reach for a ci garette. Try som e deep breathi ng i nstead. Do som e rel axati on exerci ses every tim e you feel stressed. Get hel p i f you need i t. Arrange to stop sm oki ng wi th a fri end so you can tal k about your probl ems, or joi n a stopsm oking group. If you feel desperate, you mi ght li e to tal k to a doctor or chemi st about som ethi ng to hel p you, li ke ni coti ne chewing gum. Keep tryi ng. Do not be di sappoi nted i f you have to try several ti m es before you fi nal l y stop sm oki ng. If you weaken and have a ci garete, do not feel asham ed. Just try agai n. You wil suceed eventual ly. H IV/AIDS。 crops wil l produce m ore