这些分别是什么从句?为什么?
•1.Itisprobablethat,sometimeinthetenthcentury,blackpowderwasfirst
compoundedfromitsbasicingredientsofsaltpetre,
charcoalandsulphur.
•2.Oneadvantageofbeinganonlychildisthatthereislessarguingwithinthe
family.
•3.Asimpleanalogycanhelpustounderstandhowarocketoperates.
•4.Thereisnodoubtthat“crimesagainsttheperson”riseinthesummer,whentheweatherishotterandfallinthewinter,whentheweatheriscolder.
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