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【简答题】
富马酸亚铁中铅盐的检查：取本品0.40g，置50mL烧杯中，加硝酸3mL与高氯酸5mL，加热微沸至干，冷却，加盐酸溶液（1→2）15mL，再加热微沸1分钟，放冷，移至分液漏斗中，用乙醚提取3次，每次20mL，弃取乙醚层，分取酸液，置加热，蒸去残留的乙醚，冷却，用氨试液使成碱性，加氰化钾试液1mL，加水至50mL，加硫化钠试液5滴，摇匀，与标准铅溶液2.0mL用同一方法处理后的颜色比较，不得更深（0.005%）。①乙醚提取的是什么物质？②氰化钾的作用是什么？加氰化钾前为什么要使溶液成氨碱性？③计算标准铅液的浓度（μgPb/mL）。
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【多选题】Identify which two sentences listed below contain weak and hedging expressions:
A.
For example, in January this person weighed 60.8 kg for eight days.
B.
It may be necessary for the spider to leave the branch on which it is standing, climb up the stem, and walk out along another branch.
C.
For example, it is necessary for the spider to leave the branch on which it is standing, climb up the stem, and walk out along another branch.
D.
There is experimental work to show that a week or ten days may not be long enough and a fortnight to three weeks is probably the best theoretical period.
【单选题】Section A Directions: In this section, you will hear 8 short conversations and 2 long conversations. At the end of each conversation, one or more questions will be asked about what was said. Both the ...
A.
Her computer doesn't work well.
B.
She isn't getting along with her staff.
C.
She didn't register for a proper course.
D.
She can't apply the theory to her program.
【单选题】一个海关只有同时具有 权能,才具有行政处罚权。
A.
地域管辖、级别管辖、协议管辖
B.
级别管辖、职权管辖、协议管辖
C.
地城管辖、级别管辖、职权管辖
D.
地域管辖、职权管辖、协议管辖
【单选题】已知级数 与 ,下述命题正确的是( )
A.
若级数 与 都发散，则级数 必发散。
B.
若级数 与 都收敛，则级数 必收敛。
C.
若级数 发散， 收敛，则级数 必收敛。
D.
若级数 收敛， 发散，则级数 必发散。
相关题目：
【单选题】一个海关只有同时具有 权能,才具有行政处罚权。
A.
地域管辖、级别管辖、协议管辖
B.
级别管辖、职权管辖、协议管辖
C.
地城管辖、级别管辖、职权管辖
D.
地域管辖、职权管辖、协议管辖