Wehaveknownforalongtimethatflowersofdifferentplantsopen...
問題詳情:Wehaveknownforalongtimethatflowersofdifferentplantsopenandcloseatdifferenttimeofday.Thisissofamiliarthatthereseemstobenoneedtoaskthereasonforit.Yetnoonereallyunderstandswhyflowersopenandclosel...