The entries in the Official Logbook must be signed by the Master and（）.
A. the Chief Engineer
B. the person about whom the entry concerns
C. one other crew member
D. No other signature is required
We must make a difference between（）language and（）language.
A. spoken；written
B. speaking；written
C. speaking；writing
D. speak；write
钢轨焊缝中的缺陷按其形状分可分为两大类：面积状和（）。
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