Famous 4000 mile long manmade structure in china

I think this would be the Great Wall of China!

although it's actually thought to be much, much longer: over 5000 miles long, if yoiu include natural defensive barriers used in it.

Answerwill have thinner; have thicker oceanic sediments;

The us is first  the  u.s. economy  remains the  largest in the world  in terms of nominal  gdp. however, the  u.s. economy  loses its spot as the number one  economy  to china when  measured  in terms of  gdp  based on ppp. in these terms, china's  gdp  is $23.19 trillion exceeds the  u.s. gdp  of $19.42 trillion