InthetextinsectionB,whydoestheauthorrega...c,Internetaddiction.
举一反三
- Likeanytechnology,Internethasnegativeaspectsthatbecomeclearaswestartto（）uponit.Internetaccesshasgiven（）toanewkindofsocialepidemic,internetaddiction. Afewyearsago,acoupleintheUnitedStateswascharged（）childneglect.Itwastheiraddictiontoplayinggamesonline（）keptthemfromcaringfortheirtwoinfantchildren.Anotherrecentnewsstory（）amanwhospentsomuchtimeonlinethathedidnotsleepenoughtokeephisjob.（）,helosthishousebutkepthislaptopandstillspentalldayonline. Collegestudents（）aswell.Therearemanystoriesofexcellentstudentswholosttheiruniversity（）frompoorgrades.Onestudentnotonlyfailed,（）lost12pounds.Hewasso（）onlinethatheforgottoeat!Imaginetheagonyofthiscondition!
- 比较C≡C, C=C, C─C, C=C─C=C的键长次序为: C=C─C=C>C─C> C≡C >C=C|C=C─C=C>C─C>C=C>C≡C|C≡C>C=C>C─C>C=C─C=C|C─C>C=C>C=C─C=C>C≡C|C─C>C=C─C=C>C=C>C≡C
- 下列哪种主链骨架原子排列最能代表两个肽键?() A: Cα—N—Cα—C—Cα—N—Cα—C B: Cα—N—C—C—N—Cα C: C—N—Cα—Cα—C—N D: Cα—C—N—Cα—C—N E: Cα—Cα—C—N—Cα—Cα—C
- 比较C≡C(Ⅰ),C=C(Ⅱ),C─C(Ⅲ),C=C─C=C(Ⅳ)的键长次序为( )。 A: Ⅰ＞Ⅱ＞Ⅲ＞Ⅳ B: Ⅲ＞Ⅱ＞Ⅳ＞Ⅰ C: Ⅲ＞Ⅳ＞Ⅱ＞Ⅰ D: Ⅳ＞Ⅲ＞Ⅱ＞Ⅰ
- 不稳定的一类化合物是: C≡C|C－C|C＝C|C＝C－C＝C|C＝C＝C