定期對系統和數據進行備份,在發生災難時進行恢復。該機制是為了滿足信息安全的____屬性。
A、真實性D
暫無解析
Therearen’t_____applesinthebasket,buttherearesomeonthetable
she_______(賓格)
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.
Lookoutofthewindow.(改為否定句)
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下列關于細胞的敘述,錯誤的是()