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【单选题】
光纤通信系统中常用的光电检测器主要有（ ）。A.
激光器、发光二极管
B.
分布反馈激光器、PIN光电二极管
C.
半导体PIN光电二极管、APD雪崩光电二极管
D.
PIN光电二极管、半导体激光器LD。
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反馈参考答案：
举一反三
【单选题】已知某点的运动方程为 s = a + bt 3 ( s 以米计, t 以秒计, a 、 b 为常 数),则点的轨迹 ___ __________ 。
A.
是直线
B.
是平面曲线
C.
是空间曲线
D.
不能确定
【简答题】Vocabulary Practice 1 Fill in each blank with the proper form of a word in the box convince 使确信,使信服 : 指通过行动或言语使他人从思想感情上信服 e.g. I) They convinced him of his error by sound argument. 2) The touch of...
【简答题】在含Ag+和Ag的溶液中加入氨水，溶液中[Ag+]将________(上升／下降)，φ(Ag+／Ag)将________(上升／下降)。
【简答题】某种植物种群,AA基因型个体占30%,aa基因型个体占20%,则: (1)植物的A和a基因频率分别是__________________________。 (2)若该植物自交,AA、aa后代中基因型个体分占___________、_________。这时,A、a的基因频率分别是 _________________。 (3)依据现代生物进化理论,这种植物在这一时期中是否发生了进化? ________...
【简答题】改错题。 An English lady was finally decided that she really should learn to drive, And after many attempts, she past her driving test and told her husband that, to release, he was going to drive him over...
【简答题】短文改错 A Woodman come into a forest to ask the Trees to give it a handle for Ax (斧子) . It seemed so modestly a request that the principals tree at once agreed to it, but it was settled among them that t...
【单选题】You can fly to London this evening______ you dont mind changing planes in Paris.
A.
provided
B.
except
C.
unless
D.
as soon as
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