国际金融危机的类型十分复杂，具体可分为（）。

Heat damage to fuel injection nozzles can be prevented by avoiding ____.

A.excessive fuel oil temperature

B.long periods of engine overload

C.metallic contact between nozzles and cylinder heads

D.hard carbon deposit and varnish on the nozzles

A.Brass

B.Copper

C.Lead

D.Zinc

The circular steel structure installed around the propeller of a towboat is the______．

A.nozzle

B.shroud

C.strut

D.Hood

A Kort nozzle is a(n) ______.

A.hollow tube surrounding the propeller used to improve thrust

B.nozzle attached to a firefighting hose

C.intake valve on a diesel engine

D.piston cylinder on a diesel engine

The four propellers are fitted horizontally to the Eagle.

A．Right

B．Wrong

C．Not mentioned

A．Sunday morning, 11 o'clock.

B．Thursday morning, around 10 o'clock.

C．Friday morning, around 10 o'clock.

D．Monday morning, 11 o'clock

A．Sunday morning, 11 o'clock.

B．Thin, day morning, around 10 o'clock.

C．Friday morning, around 10 o'clock.

D．Monday morning, 11 o'clock

A.fixed pitch propellers

B.uncontrollable pitch propeller

C.constant pitch propellers

D.variable pitch propellers