One nautical mile is the length of an arc of great circle which subtends an angle of ()at the centre of the earth.
A. 1 degree
B. 1 minute
C. 1 second
D. 1.5 degree
Which of the following is TRUE of advection fog ().
A. It commonly occurs on coastal waters during cold seasons
B. It moves in a bank or dense cloud
C. It is caused by warmer air moving to a cooler location
D. All of the above
申请领取许可证的辐射工作单位从事使用()类射线装置活动的，应当组织编制环境影响报告书。
A. Ⅰ
B. Ⅱ
C. Ⅲ
D. Ⅰ、Ⅱ
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