Wehaveknownforalongtimethatflowersofdifferentplantsopen...
问题详情:Wehaveknownforalongtimethatflowersofdifferentplantsopenandcloseatdifferenttimeofday.Thisissofamiliarthatthereseemstobenoneedtoaskthereasonforit.Yetnoonereallyunderstandswhyflowersopenandclosel...