第1题
第4题
途中控制噪汽车在行驶时,发动机因______而产生较大的噪声.减少噪声的主要途径有:①在声源处控制噪声;②在传播途中控制噪声;③在人耳处减弱噪声.人们在发动机周围安装带有很多小孔的吸音棉,这是通过上述第______种途径减少噪声的.当声音传进小孔,就会由于摩擦而被减弱.这个过程中声能转化为______能.
第7题
第12题
re delivery, he carried out the initial Safety Equipment survey in accordance with the Fire Fighting and Life-saving Control Plan.Surveyor noted that the vessel had two ()
A.The surveyor’s comment was not correct; because the Life-raft has the Hydra-Static Releaser, should not care the height of Storing Position
B.The surveyor’s comment was correct; because if the Storing height was over the Limit of the Life-raft, It may damage the Life-raft when throwing off to the water
C.The surveyor’s comment was not correct; the storing position was the same location as showing on the approved drawings
D.The surveyor’s comment was correct; as a surveyor, he can give any comment as he like
第13题
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