projectionn.投影；投射；规划；发射；凸出物；预测；放映projection center投影中心projection systemn.投射系统；投影系统projection effect投影效应projection length拽脚projection wekder[机] 浮凸熔接机projection method投影法projection welder凸焊机projection theory投影原理projection TV set投影电视机projection optics投射[投影]光学(系统)