当船舶从前进工况改为倒航工况时:()
A.主机功率变化,船体阻力不变
B.船体阻力变化,主机功率不变
C.船体阻力不变,螺旋桨推力变化
D.船体阻力、主机功率都变化
参考答案:D
Though my uncle lives in the USA, he often _____ his family. [ ]
A. thinks for
B. thinks of
C. thinks out
D. thinks over
()属于集中荷载.
A.洗衣机
B.冰箱
C.空调机
D.以上都是