单项选择题
A.the higher B.the lower C.the faster D.the slower
When viewed from astern, if the propeller revolves in a...
单项选择题When viewed from astern, if the propeller revolves in a clockwise direction when going ahead, it is known as （）.
A.ahead direction B.astern direction C.right-handed D.left-handed
The pitch ratio of a propeller is the mean pitch divide...
单项选择题The pitch ratio of a propeller is the mean pitch divided by （）.
A.the propeller diameter B.the propeller radius C.the pitch angle D.the length of helix
If a line at right angles to the axis rotates about tha...
单项选择题If a line at right angles to the axis rotates about that axis and, at the same time, moves parallel to the axis, it will generate （）.
A.a helix B.a helicoidal C.a curve D.a cone
