有关键码值为 10, 20. 30 的三个结点，按所有可能的插入顺序去构造二叉排 序树。能构造出多少棵不同的二叉排序树?
A、4B
暂无解析
Acartravelsatarateof50milesperhour.Howlongwillittaketotravel300miles?
()Whatabout__________?
()Pleasegivemetwobottlesof_______.
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.
()1.Don'tbelateagain.A.Anewwatch.
()2.MayIhaveacupoftea?B.Me，too.
()3.Iliketheredfan.C.Isee.
()4.What'sthatonthedesk?D.Sure.
()5.Where'sDad?E.Perhapshe'sinthestudy.
()6.Shallwegotothezoobybike?F.It'sBob's，Ithink..
()7.Whosekiteisthis?G.Goodidea.
()8.CanIhavealookatyourdress?H.Yes.Hereyouare.
