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【单选题】
以下属于多模光纤的传输波长的是 ( ) 。A.
850nm
B.
13l0nm
C.
1550nm
D.
l300nm
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参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【多选题】下列哪些选项属于民用航空器同国家航空器相比具有下列哪些明显的特征:
A.
民用航空器一般从事运送旅客、行李、货物和邮件等公共航空运输的工作
B.
民用航空器一般从事工农林渔和建筑业的作业飞行
C.
民用航空器一般从事医疗卫生和采取保健措施
D.
民用航空器一般从事教育训练、文化体育等飞行活动
【单选题】What did they do when they were together?
A.
They talked about a lot of things.
B.
The speaker cooked for the old lady.
C.
They did some gardening.
D.
They talked about their families.
【单选题】Though it is the first time they have met, they talked as if they _____ friends for many years.
A.
are
B.
were
C.
had been
D.
have been
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