The term of Landfall means().
A. Land first sighted when vessel approaching from seaward
B. Land last sighted when vessel leaving from a port
C. in sight of one another when vessel underway
D. in sight of an island during a ship on her voyage
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集成电路彩色电视接收机中,设计有一个自动消色电路,当接收黑白电视信号,或者()时,自动关闭色度通道。
A. 彩色电视信号较强
B. 彩色电视信号较弱
C. 亮度和饱和度太强
D. 亮度和饱和度太弱
楼梯的组成部分不包括()
A. 踏步
B. 梯段
C. 平台
D. 栏杆