Explain how use of EGR is effective in reducing NOx emissions 4. In most locations throughout the U. S., the octane number of regular grade gasoline [defined as (R+M)/2] is 87. However, in certain high elevation locations (parts of CO, ID, MT, UT, and WY) regular gasoline may have a lower octane value of 85. Explain how a lower octane fuel can be used in these areas without it leading to unacceptable knocking

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explanation:

answer:

the correct answer is d

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Explanation:

key points:

• The Dubai Mall is the largest mall in the world.

• Area : the same as 50 football pitches and more than 1200 shops.

• ground floor have an aquarium, named Dubai Aquarium, the world's largest indoor aquarium.

• aquarium with 33 000 aquatic animals including sharks.

• outside the Mall, have fountains, named Dubai Fountains with water jets of approximately 200 metres long.

• can visit Olympic sized ice-skating rink.