翻译短文： Have you ever heard someone use the phrase "once in a blue moon "? People
翻译短文：Haveyouever heardsomeoneusethephrase"onceinabluemoon "?Peopleusethisexpression todescribesomethingthattheydonotdoveryoften. Forexample,somethingmightsay thathetrisetoavoideating sweetdbecausetheyareunhealthy,butwilleatchocolate"onceinabluemoon" . Orsomeonewhodoesnotusuallyliketogotothebeachmightsay"Ivisittheshoreonceinabluemoon." Whilemanypeopleusethisphrase,noteveryoneknowsthemeaningbehindit.
The first thingtoknowisthatthemoonitselfisneverreallyblue .Thisisjustanexpression .Infact, thephrase "bluemoon" hastodowiththeshapeofthemoon, notthecolor.
Asthemoon travelsaroundtheearth ,itappearstochangeshape.Weassociatecertainnameswithcertainshapesofthemoon.Forexample,whenwecanseeasmallpartofthemoon,itiscalledacrescentmoon.Acrescentisashapethatlookslikethetipofafingernail.Whenwecannotseethemoonatall,itiscalledafullmoon.Usually ,thereisonlyonefullmooneverymonth.Sometimes,however,therewillbetwofullmoonsinonemonth .Whenthishappens,thesecondfullmooniscalledinonemonth . Whenthishappens,thesecondfullmooniscalleda"abluemoon. "