问题
单项选择题
Vessels are warned（）in the area enclosed by pecked lines owing to the existence of numerous telegraph cables.
A.anchor
B.to anchor
C.not to anchor
D.not to anchoring
答案
参考答案：C
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Vessels are warned（）in the area enclosed by pecked lines owing to the existence of numerous telegraph cables.
A.anchor
B.to anchor
C.not to anchor
D.not to anchoring
参考答案：C
（3）碘是一种人体必需的微量元素，碘元素在周期表中的信息如右图所示。