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【单选题】
工具书库开放时间是?A.
8:00——21:00
B.
9:00——22:00
C.
8:20——22:00
D.
正常上班时间
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参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】下面说法正确的是
A.
若 在 处存在极限，则 在 处连续
B.
若 在 处无定义，则 在 处无极限
C.
若 在 处连续，则 在 处存在极限
D.
若 在 处连续，则 在 处可导
【简答题】创建建工墙体练习
【单选题】How many feedback resistors are found in a 3-input voltage summing circuit that is constructed around an op-amp?
A.
0
B.
1
C.
2
D.
3
【多选题】How do voltage-gated ion channels work?
A.
Voltage-gated ion channels have domains called voltage sensors that are extremely sensitive to changes in the membrane potential: changes above a certain threshold value exert sufficient electrical force on these domains to encourage the channel to switch from its closed to its open conformation.
B.
A change in the membrane potential does not affect how wide the channel is open, but instead alters the probability that it will open. Thus, in a large patch of membrane containing many molecules of the channel protein, one might find that on average 10% of them are open at any instant when the membrane is at one potential, whereas 90% are open after this potential changes.
C.
When one type of voltage-gated ion channel opens, the membrane potential of the cell can change. This in turn can activate or inactivate other voltage-gated ion channels.
D.
Such circuits, which couple the opening of ion channels to changes in membrane potential to the opening of additional ion channels, are fundamental to all electrical signaling in cells.
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