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ot　live　for　more　than　a　few　minutes　without　air.　We　take　in　air.　When　we　are　working　or　running　we　need　more　air.　When　we　are　asleep，　we　need　less　air.　We　live　in　air，　but　we　cannot　see　it.　We　can　only　feel　it　when　it　is　moving.　Moving　air　is　called　wind.　How　can　we　make　air　move?　Here　is　one　way.　Hold　an　open　book　in　front　of　your　face，　close　it　quickly.　What　can　you　feel?　What　you　feel　is　air.

Passage　29.Clocks

There　are　many　clocks　in　the　Brown’s　house.　They　are　in　different　rooms.A　big　clock　stands　in　a　corner　of　the　sitting　room.　It　is　a　very，　very　old　clock，　but　it　still　keeps　good　time.　Mr.　Brown　winds　it　once　a　week.

Passage　30.　Swimming

Swimming　is　a　good　sport.　It’s　popular.　People　like　swimming　because　the　water　makes　people　feel　cool.　But　if　they　swim　in　a　wrong　place，　it　is　very　dangerous.　These　years，　some　people　died　when　they　were　enjoying　themselves　in　water　and　most　of　them　were　students.　Summer　holiday　will　be　there　again.　I　want　to　give　you　some　advice.　First，　don’t　get　into　the　water　when　you　are　alone.　Second，　don’t　get　into　the　water　if　there　is　a　No　swimming　sign.　Third，　you　should　be　careful　in　the　water.　If　you　remember　these，　swimming　will　be　safe　and　it’s　good　for　your　health.

Modern　Technologies

We’re　all　enjoying　the　conveniences　and　happiness　brought　by　modern　technologies.　We　use　telephones　and　mobile　phones　to　call，　emails　to　write　and　vehicles　to　drive；　we　go　to　another　country　by　air　planes；　we　see　what　is　happening　in　the　world　by　TV　programs　and　Internet，　and　we　even　watch　sports　games　on　live.　Nowadays，　without　these　technologies，　I　can’t　imagine　what　my　life　could　be.

I　used　to　read　an　article　describing　the　modern　lives　of　human　beings.　It　says　we　will　have　many　phone　numbers　if　we　want　to　search　for　one　person；　we　send　emails　and　cell　phone　messages　to　our　friends　in　stead　of　visiting　them.　More　and　more　people　would　rather　sit　in　front　of　a　computer　than　a　TV.　And　we　seldom　go