单项选择题
Which action（s）is/are included in crane operations（）.
A.Normal boom stowage and shutdown operations B.Emergency shutdown operation C.Removing booms from stowage D.All of the above
单项选择题 What is a“Special Warning”（）.
单项选择题 What form of ice is of land origin（）.
单项选择题 We have no steel wire．You had better（）us one.
