太阳能电池是把太阳辐射光能通过（）转换成电能的光—电转换器。
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以下哪种系统转换方式的风险较小（）。
A. 直接转换
B. 平行转换
C. 分段转换
Which statement is TRUE concerning a vessel equipped with operational radar?（）.
A. She must use this equipment to obtain early warning of risk of collision
B. The use of a radar excuses a vessel from the need of a look-out
C. The radar equipment is only required to be used in restricted visibility
D. The safe speed of such a vessel will likely be greater than that of vessels without radar
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