问题
单项选择题
上变频器通常采用2次变频方式，为了避免镜像信号和杂散信号干扰，通常将第二中频选在（）范围内。
A.70-140MHz
B.140-700MHz
C.700-1120MHz
D.140-1120MHz
答案
参考答案：C
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上变频器通常采用2次变频方式，为了避免镜像信号和杂散信号干扰，通常将第二中频选在（）范围内。
A.70-140MHz
B.140-700MHz
C.700-1120MHz
D.140-1120MHz
参考答案：C
An investor buys a call option with a $25 exercise price priced at $4 and writes a call option with a $40 exercise price priced at $2.50. If the Price of the stock increases to $50 at expiration and the options are exercised on the expiration date, the net profit at expiration (ignoring transaction costs) is:
A．
| A. $8.50. |
B．
| B. $13.50. |
C．
| C. $16.50. |
