一个网络可以由两台计算机组成，也可以由在同一大楼里面的上千台计算机组成。我们通常把这样的网络称为局域网(LAN)，由LAN再延伸出去形成更大的范围，比如整个城市，这样的网络我们称之为广域网(WAN)。一个计算机网络的主要组成部分包括()。

A.apparent slip

B.true slip

C.pitch

D.propulsive efficiency

Compared to a constant pitch propeller, a controllable pitch propeller

A.more efficiently uses available engine power

B.operates at a lower efficiency at a fixed speed

C.produces the same torque at lower engine power

D.develops its rated power at a lower speed

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

Why a gearbox is needed in a ship driven by a medium-speed diesel engine？ .

A.To reduce the main engine speed

B.To increase the main engine speed

C.To govern the main engine speed

D.To fix the propeller shaft

as _____.

A.the speed of the vessel

B.the speed of the propeller

C.the wake

D.the wake fraction

When ship navigating in rough sea, the correct operation is .

A.navigating with a low diesel engine speed

B.navigating with a stable diesel engine speed

C.increasing the efficiency of propeller

D.increasing fuel injection

A. the extra weight required for the diesel reduction gearing

B. a minimum speed for the engines that limits the minimum speed of the vessel

C. the higher fuel consumption per SHP

D. the low efficiency of the system when a controllable pitch propeller is used

eed of 11 knots (339.79m/min), will give _____ of apparent slip.

A.0.967

B.0.033

C.0.031

D.0.969

The speed of main engine to be reducedIIShip speed to be reducedIIIThe resistance torque of propeller to be increasedIVTrim at stern to increase.

A.I + II

B.I ~ III

C.I ~ IV

D.I + II + IV