假山是由人工构筑的仿自然山形的土石砌体，是一种仿造的山地环境。
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Which of the following statements is FALSE concerning cranes being installed on the centerline of vessels（）.
A centerline crane can never be operated in tandem
B. One crane is able to work one end of two adjacent hatches
C. These cranes are more economical and weigh less than outboard-mounted cranes
D. One crane is able to work both sides of the shi
铺设无缝线路应有无缝线路铺设位置配轨图表、（）、锁定轨温范围及有关设计计算书。
前飞时，由于桨叶的周向气流速度不对称引起的挥舞运动，使（）方位的桨叶挥舞最高。
A. 90°
B. 180°
C. 0°
根据（）的建议，国内有效号码的长度不超过（）位，国际有效号码长度不超过（）位。
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