The general purpose of a heat exchanger is to （）.

A . prevent an internal explosion in the pump when it is overheated B . enable a visual inspection of the pump while it is running C . insure a proper alignment of the pump coupling to the driver D . accommodate for friction between the impeller and the easing

A . remove any air that may accumulate in the system B . take out unpleasant fumes from the refrigerant C . vent off excess refrigerant in an emergency D . permit opening the refrigerating system for cleaning and inspecting

A . act as a chain stopper B . prevent the windlass from engaging C . prevent the chain from fouling on deck D . control the wildcat

A . produce the heat for ignition B . decrease injection lag C . increase ignition delay D . aid in exhausting burnt gase

A . afford access to the shell through the double bottoms B . collect water to be pumped out C . provide access for the pneumercator D . provide a base line for sounding measurement

A . counterbalance the crank throws on the crankshaft B . keep the engine running smoothly between power stroke C . provide a belt-driving surface for the operation of auxiliary machinery D . prevent the engine from overspeeding

A . acts as a meeting place for sources and receivers of multicast traffic B . used in PIM dense m ode to create a database of all multicast sources C . used in PIM dense and sparse mode to create a database of all multicast sources D . acts as the designated router for a broadcast segment when multicast routing is enabled

A . is B . be C . will be D . to be

A . help preheat the air for the furnaces B . help preheat the feedwater C . protect economizer from excessive heat D . prevent excessive furnace heat losse

A . it is not used in multicast B . it determines the virtual address group for a multicast destination C . it dynamically registers individual hosts in a multicast group on a specific LAN D . it is used on WAN connections to determine the maximum bandwidth of a connection E . it determines whether Bidirectional PIM or PIM sparse mode will be used for a multicast flow

A . It allows for rotation of the hook in the single mode B . It is required to“twin-up”30-ton pedestal cranes C . It is used to pick up light loads D . It is used to rigidly connect two crane

A .  it is not used in multicast B .  it determines the virtual address group for a multicast destination C .  it dynamically registers individual hosts in a multicast group on a specific LAN D .  it is used on WAN connections to determine the maximum bandwidth of a connection E .  it determines whether Bidirectional PIM or PIM sparse mode will be used for a multicast flow

A . Provides surface for applying force on machinery B . Provides landing surface for the sounding bob C . Absorbs machinery vibration D . Prevents valve stem over-travel

A . present Cisco products B . provide a framework of tested and proven models C . identify basic needs of the business D . calculate the business need priority

A . Aid in casting off B . Direct the drift of the vessel C . Aid in its recovery D . Maintain maximum resistance to broaching

A．To do scientific research. B．To show his strength. C．To explore a dangerous place. D．To know more about Antarctica.

A．show the direction in which the imaginary cut surface is viewed B．indicate the location of the cutting plane C．identify the reference letters such as section A-A or B-B,etC D．all of the above

A．To inform B．To persuade C．To criticize

A．to persuade B．to entertain C．to explain