The crane jib is raised and lowered by

1、What is/are the advantage（s）of cranes

What is/are the advantage（s）of cranes over conventional cargo booms（）.ACranes are able to pick up and drop loads over a greater spotting are...

2、The lower section of a piston is calle

The lower section of a piston is called the （）.AlandBskirtCcrownDplate

3、（）is the process by which the position

（）is the process by which the position of the vessel at any moment is found by applying the last well-determined position to the run that ...

4、（）is taken from the lower most point o

（）is taken from the lower most point of the keel to the summer loadline.AExtreme draftBMolded draftCExtreme depthDMolded depth

5、The tackle that raises and lowers the

The tackle that raises and lowers the boom is（）.Athe cargo fallBThe cargo hoisting wire ropeCthe topping liftDthe cargo whi

6、The lower end of each piston rod is re

The lower end of each piston rod is reduced in diameter to fit a bore in （）, this being secured to the piston rod by a nut.Athe crank-webBthe connecting rodCthe main bearingDthe cross-head