{{i}} quEstions 4 to 7 ArE BAsED on thE Following ConvErsAtion.At thE EnD oF thE ConvErsAtion, you will BE givEn 20 sEConDs to AnswEr thE quEstions. now listEn to thE ConvErsAtion.{{/i}}

whAt ArE thE spEAkErs mAinly DisCussingAn ExpErimEnt inAntArCtiCA、
B．pArt oF thE lArsEn iCE shElF BrokE oFF.
C．thE FormAtion oF thE lArsEn iCE shElF.
D．An ExpEDition inAntArCtiCA、