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將某種酶運(yùn)用到工業(yè)生產(chǎn)前，需測定使用該酶的最佳溫度范圍。下圖中的曲線①表示在各種溫度下該酶活性相對于最高酶活性的百分比。將該酶在不同溫度下保溫足夠長的時間，再在酶活性最高的溫度下測其殘余酶活性，由此得到的數(shù)據(jù)為酶的熱穩(wěn)定性數(shù)據(jù)，即下圖中的曲線②。據(jù)此作出的判斷，錯誤的是

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.

下列圖例符號與其所表示的礦產(chǎn)地搭配準(zhǔn)確的一組是()

已知阿伏伽德羅常數(shù)是NA，銅的摩爾質(zhì)量為M，銅的密度是ρ，那么以下說法正確的是()

因為人類活動引起的環(huán)境問題是()