Please answer the following three questions
1) Define the major parts of a exhaust system.
2) Identify the main ways of emission control system.
3) Identify working principle of catalytic converter.
2. Translate the following sentences into Chinese
1) Automotive emissions are controlled in three ways. One is to promote morecomplete combustion so that there are less by-products. The second is to reintroduceexcessive hydrocarbons back into the engine for combustion and the third is to provide anadditional area for oxidation or combustion to occur. This additional area is called acatalytic converter.
2) The purpose of the positive crankcase ventilation（PCV) system is to take thevapors away produced in the crankcase during the normal combustion process，and redirectthem into the air/fuel intake system to be burned during combustion.
3) An evaporative control system was developed to eliminate this source of pollution.The function of the fuel evaporative control system is to trap and store evaporativeemissions from the gas tank and carburetor.
·4) The need to control the emissions from automobiles gave rise to the computerization ofthe automobile. Hydrocarbons，carbon monoxide and oxides of nitrogen are created duringthe combustion process and are emitted into the atmosphere from the tail pipe. There arealso hydrocarbons emitted as a result of vaporization of gasoline and from the crankcase ofthe automobile.
5) They were called feedback fuel control systems. An oxygen sensor was installed inthe exhaust system and would measure the fuel content of the exhaust stream. It thenwould send a signal to a microprocessor, which would analyze the reading and operate afuel mixture or air mixture device to create the proper air/fuel ratio.