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【判断题】
在数据链路层,封装成帧是指仅需要在数据尾部加帧结束标记。( )A.
正确
B.
错误
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举一反三
【单选题】CaC 2 O 4 的 K sp = 2.6 ́ 10 -9 , 在含 0.020 mol·dm -3 Ca 2+ 的溶液中形成沉淀时 , 所需 离子浓度至少应为 ( )
A.
1.1 ´ 10 -9 mol·dm -3
B.
1.3 ´ 10 -7 mol·dm -3
C.
2.2 ´ 10 -5 mol·dm -3
D.
2.2 ´ 10 -7 mol·dm -3
【单选题】So ____ that no fish can live in it.
A.
the river is shallow
B.
shallow the river is
C.
shallow is the river
D.
is the river shallow
【单选题】CaC 2 O 4 ( K sp =2.32 ×10 -9 )在 0.1 mol × L -1 的 CaCl 2 溶液中的溶解度为( )
A.
4.81 ×10 - 5 mol × L -1
B.
1.32 ×10 - 3 mol × L -1
C.
8.34 ×10 - 4 mol × L -1
D.
2.32 ×10 - 8 mol × L -1
E.
1.16 ×10 - 8 mol × L -1
【单选题】.—What should we do to protect the fish in the river? —We throw rubbish into the river.
A.
mustn’t
B.
have to
C.
must
D.
needn’t
【单选题】Not until all the fish died in the river how serious the pollution was.
A.
did the villagers realize
B.
the villagers realized
C.
the villagers did realized
D.
didn't the villagers realized
【单选题】CaC 2 O 4 的 K sp 为 2.6×10 - 9 ,要使 0.020 mol.dm - 3 CaCl 2 溶液生成沉淀,需要的草酸根离子浓度是 ( )
A.
1.3×10 － 7 mol.dm － 3
B.
1.0×10 － 9 mol.dm － 3
C.
5.2×10 － 10 mol.dm － 3
D.
2.2×10 － 5 mol.dm － 3
【单选题】Not until the fish died in the river how serious the pollution was.
A.
did the villagers realize
B.
the villagers realized
C.
the villagers did realize
D.
didn’t the villagers realize
【简答题】Sometimes in the afternoon, I, together with my cousins, went to the river to fish.
【简答题】连词成句，我最棒！ 1. a live does where zebra ? 2. is judge a the monkey . 3. lives the river fish in a . 4. live a does a snake in hole ? 5. animal ...
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