根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。Obtaining fresh water from icebergs
The idea of getting fresh water fromicebergs that are moved to populated areas or places was once treated as ajoke.Recently, scientists have warned that the human race will outgrow itsfresh water supply faster than it runs out of food. {#blank#}1{#/blank#}
Glaciers are a possible source offresh water that has been overlooked until recently.{#blank#}2{#/blank#}It contains fresh water so much thatit could sustain all the rivers of the world for 1，000 years.
Huge glaciers that stretch over theshallow continental shelf give birth to icebergs throughout the year.{#blank#}3{#/blank#}However, they are formed entirely onland, breaking off when glaciers spread over the sea.As they drift away fromthe polar region, icebergs sometimes move mysteriously in a direction oppositeto the wind.Because they melt more slowly than smaller pieces of ice, icebergshave been known to drift as far north as 35 degrees south of the equator in theAtlantic Ocean.
{#blank#}4{#/blank#}The difficulty exists such as itsrapid melting in warmer climates.{#blank#}5{#/blank#}
a．Icebergsare not like sea ice, which is formed when the sea itself freezes.
b．Nowit is being considered quite serious by many nations.
c.7，659 trillion metric tons of ice isfloating on the sea every year.
d．Butthe water they could provide would be far cheaper than that produced.
e．Tomove them to try parts of the world would not be too difficult.
f．Itis not a dream to get water from Icebergs.
g．Threequartersof the Earth's fresh water supply is still tied up in glacial ice.
