拉脱维亚的首都是哪？

A. the method for the proper stowage of a dangerous cargo
B. the necessity of lashing，securing and piling of awkward or lengthy cargo
C. whether different goods can be stowed together in one hold
D. ventilation method for hydrous cargo

A. 主令手柄
B. 按钮及指示灯
C. 液晶显示屏
D. 通讯模块