单项选择题
The characteristic of a lighted cardinal mark may be （）.
A.very quick flashing B.flashing C.fixed D.occulting
单项选择题 Temperature and moisture characteristics are modified in a warm or cold air mass due to （）.
单项选择题 Please wireless to let me know （） I am to anchor or to meet pilot．
单项选择题 Place names used should be those （）.
