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	<question>
		<phrase isaudiomp3="1" mp3="AUDIO_REPOS/8.0.mp3"></phrase>
		<question isaudiomp3="1" rationale="0" picture="images/question8.jpg" mp3="AUDIO_REPOS/2063-8" exercise_type="" questionmode="" choicemode="" answerbankid="" answerbankmode="" rationalemode="" playonload="" mp3speed="" ttsspeed="" passage="1" show_passage="" show_passage_audioplayer="" passage_audio_type="" showvideo="" video="" enable_audio_recorder="" recorder_mode=""><![CDATA[]]></question>
		<saythis><![CDATA[]]></saythis>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/8.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[Most scientists believe the shergottites were formed as a result of volcanic activity about 150 to 250 million years ago.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/9.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[This would place their formation during Earth's Jurassic period, when dinosaurs roamed the Earth.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/10.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[If so, shergottites are a sign that Mars might have been geologically active fairly recently.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/11.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[That in turn means it might still have been hospitable to some form of life, said Munir Humayun, a planetary geochemist at Florida State University who was not involved in the study.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/12.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[But a few researchers recently estimated that shergottites are actually about 4 billion years old  -  a finding that had far-reaching implications for scientists' understanding of Martian history."]]></answer>
	</question>
	
	<question>
		<phrase isaudiomp3="1" mp3="AUDIO_REPOS/20.0.mp3"></phrase>
		<question isaudiomp3="1" rationale="0" picture="images/question20.jpg" mp3="AUDIO_REPOS/2063-20" exercise_type="" questionmode="" choicemode="" answerbankid="" answerbankmode="" rationalemode="" playonload="" mp3speed="" ttsspeed="" passage="1" show_passage="" show_passage_audioplayer="" passage_audio_type="" showvideo="" video="" enable_audio_recorder="" recorder_mode=""><![CDATA[]]></question>
		<saythis><![CDATA[]]></saythis>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/20.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[That's why scientists picked the tiny baddeleyites: Once they form, they are durable little minerals.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/21.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[It's not easy to melt them down and reset their isotopic clock.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/22.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[By looking at the isotopic ratios of radioactive uranium and lead in this tough rock, the scientists found that it formed about 187 million years ago, give or take 33 million years.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/23.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[This confirmed that the baddeleyites were young.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/24.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[The scientists could also see evidence of the damage done to the meteorite by the event that may have released it from the Martian surface sometime around 22 million years ago.]]></answer>
		<answer isaudiomp3="1" picture="images/c1.jpg" mp3="AUDIO_REPOS/2063-1" isrationalemp3="1" rationalemp3="AUDIO_REPOS/right.mp3" rationaleimage="images/rationale/25.1.jpg" rationale="Right" value="1" choicesay=""><![CDATA[The shock from that impact muddled up the mineral structure inside, while keeping the chemicals themselves mostly intact.]]></answer>
	</question>

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