已知一个梯形的面积是58平方厘米，它的上底是15厘米，下底是25厘米，它的高是多少厘米?
解：58× 2(÷15+25)
=116÷ 40
=2.9(厘米)，
答：它的高是 2.9 厘米
暂无解析
JackisateacherofEnglish.Heisnotyoung，butheisnotold.Hehasaroundfaceandblackhair.Heistall.Therearefiftystudentsinhisclass.Theyalllikehim.Nowit'sintheafternoon.Look，somestudentsareworkingintheclassroom.Jackisthere，too.HeishelpingthemtostudyEnglish.Heisagoodteacher，andheisagoodfriendofthemall.
()1.WhatdoesJackdo?
A.Heisaworker.
B.Heisateacher.
C.Heisadoctor.
D.He'sanurse.
()2.Whatcolourishishair?
A.It'sblack.
B.Hisheiriswhite.
C.Itisbrown.
D.Hehasyellowhair.
()3.Howmanystudentsarethereinhisclass?
A.Therearefifteenstudentsinhisclass.
B.There'sfifty.
C.Hehasfifty.
D.There'refiftyinit.
()4.Jackisagoodteacher，isn'the?
A.Yes，heisn't.
B.No，heis.
C.Yes，he's.
D.Yes，heis.
()5.Whatarethestudentsdoingintheclassroom?
A.Theyarewalkingthere.
B.Theyaredoingtheirlessons.
C.Theyarehelpingtheirteacher.
Theboysaresittingunderthetree.(对划线部分提问)
___________________________________________
Ice-creamandcandiesarenothealthyfood.Theyaleu_____food
Linglingisin__________.
在1﹣20中，既是奇数又是质数的数，有()个.
