Xav paub ntau ntxiv ...
Thaum kuv thawj zaug mus xyuas Chicago nrog kuv niam kuv txiv xyoo dhau los, peb tau mus ntsib Sears Tower (tam sim no hu ua Willis Tower). Taug kev cov blocks mus rau lub tsev thiab saib - koj pib xav txog qhov xav tsis thoob ntawm engineering nws yog dab tsi. Nws yog 4.56 lab tag nrho cov square feet, 110 zaj dab neeg siab, siv 3 xyoo rau…