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【单选题】
以下关于光纤特性的叙述中，正确的是（ ）
A.
光纤传输信号无衰减
B.
光纤传输速率无限制
C.
光纤传输的抗干扰能力比较强
D.
光纤传输距离无限制
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参考答案：
举一反三
【单选题】Why would policy makers need to regulate all firms that produce differentiated products?
A.
Because such products are so common in the economy.
B.
Because there is no easy way for policymakers to fix the problem.
C.
Because they want to enforce marginal-cost pricing.
D.
Because monopolistic competitors are making zero profits.
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【单选题】设对某角观测一测回的中误差为 ±3′′ ,要使该角的观测精度达到 ±1.4′′ ,需观测 ( ) 个测回。
A.
2
B.
3
C.
4
D.
5
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【判断题】盐酸羟胺-吡啶肟化法测定羰基化合物含量时，加入吡啶的目的是与生成的盐酸结合以降低酸的浓度，抑制逆反应。
A.
正确
B.
错误
查看完整题目与答案
【判断题】“纸黄金”是一种个人凭证式黄金,投资者按银行报价在账面上买卖“虚拟”黄金,个人通过把握国际金价走势低吸高抛,赚取黄金价格的波动差价。
A.
正确
B.
错误
查看完整题目与答案
【判断题】盐酸羟胺吡啶肟化法测定羰基化合物含量时,加人吡啶的目的是与生成的盐酸结合以降低酸的浓度,抑制逆反应,()
A.
正确
B.
错误
查看完整题目与答案
【单选题】听力原文：We've been living through times of plenty in recent decades, but no more. World grain sup- plies are low, there's just forty days' worth in stock and the long-term future looks bleak. Our demand ...
A.
There is plenty of grain in the world and people need not to worry about it.
B.
The world's population is estimated to explode from over 6 billion now to 19 billion by 2050.
C.
The population increase is mainly in undeveloped countries.
D.
World demand for foods is predicted to rise 50% by 2030.
查看完整题目与答案
【单选题】It has been challenging for most twentieth-century American policy-makers to recapture the memory of the early United States, Constitution and all, as a revolutionary force-to ascertain, in other word...
A.
Ⅰ only
B.
Ⅱ only
C.
Ⅰ and Ⅱ only
D.
Ⅱ and Ⅲ only
E.
Ⅰ,Ⅱ, and Ⅲ
查看完整题目与答案
【单选题】下列对象执行偏移命令后，大小和形状保持不变的是（ ）。
A.
圆弧
B.
直线
C.
正方形
D.
圆
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【单选题】Ag-DDC法检查砷盐的原理为:砷化氢与Ag-DCC、吡啶作用,吡啶作用,生成红色物质
A.
砷盐
B.
锑斑
C.
胶态砷
D.
胶态银
查看完整题目与答案
【单选题】. A look at recent trends in world fisheries reveals ________ the ocean on a global scale.
A.
how we have swiftly affected
B.
that how swiftly we have affected
C.
how swiftly we have affected
D.
however swiftly we have affected
查看完整题目与答案
相关题目：
【单选题】Why would policy makers need to regulate all firms that produce differentiated products?
A.
Because such products are so common in the economy.
B.
Because there is no easy way for policymakers to fix the problem.
C.
Because they want to enforce marginal-cost pricing.
D.
Because monopolistic competitors are making zero profits.
查看完整题目与答案
【单选题】设对某角观测一测回的中误差为 ±3′′ ,要使该角的观测精度达到 ±1.4′′ ,需观测 ( ) 个测回。
A.
2
B.
3
C.
4
D.
5
查看完整题目与答案
【判断题】盐酸羟胺-吡啶肟化法测定羰基化合物含量时，加入吡啶的目的是与生成的盐酸结合以降低酸的浓度，抑制逆反应。
A.
正确
B.
错误
查看完整题目与答案
【判断题】“纸黄金”是一种个人凭证式黄金,投资者按银行报价在账面上买卖“虚拟”黄金,个人通过把握国际金价走势低吸高抛,赚取黄金价格的波动差价。
A.
正确
B.
错误
查看完整题目与答案
【判断题】盐酸羟胺吡啶肟化法测定羰基化合物含量时,加人吡啶的目的是与生成的盐酸结合以降低酸的浓度,抑制逆反应,()
A.
正确
B.
错误
查看完整题目与答案
【单选题】听力原文：We've been living through times of plenty in recent decades, but no more. World grain sup- plies are low, there's just forty days' worth in stock and the long-term future looks bleak. Our demand ...
A.
There is plenty of grain in the world and people need not to worry about it.
B.
The world's population is estimated to explode from over 6 billion now to 19 billion by 2050.
C.
The population increase is mainly in undeveloped countries.
D.
World demand for foods is predicted to rise 50% by 2030.
查看完整题目与答案
【单选题】It has been challenging for most twentieth-century American policy-makers to recapture the memory of the early United States, Constitution and all, as a revolutionary force-to ascertain, in other word...
A.
Ⅰ only
B.
Ⅱ only
C.
Ⅰ and Ⅱ only
D.
Ⅱ and Ⅲ only
E.
Ⅰ,Ⅱ, and Ⅲ
查看完整题目与答案
【单选题】下列对象执行偏移命令后，大小和形状保持不变的是（ ）。
A.
圆弧
B.
直线
C.
正方形
D.
圆
查看完整题目与答案
【单选题】Ag-DDC法检查砷盐的原理为:砷化氢与Ag-DCC、吡啶作用,吡啶作用,生成红色物质
A.
砷盐
B.
锑斑
C.
胶态砷
D.
胶态银
查看完整题目与答案
【单选题】. A look at recent trends in world fisheries reveals ________ the ocean on a global scale.
A.
how we have swiftly affected
B.
that how swiftly we have affected
C.
how swiftly we have affected
D.
however swiftly we have affected
查看完整题目与答案
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