单项选择题 Generally speaking，the most favorable bottom for anchoring is（）.

单项选择题 During an annual FCC inspection（）.

单项选择题 Downwind for 1 miles，alter to starboard 90 degrees，go down this course for 1 mile；Then alter 90 degrees to starboard and go down this course for 2 miles；Then alter 90 degrees to starboard and go down this course for 2 miles；Keep adding 1 mile ever time you alter to starboard．This operation is（）search pattern