It is a polyurethane-polyurea copolymer that was co-invented in 1959 by chemists C. L. Sandquist and Joseph Shivers at DuPont's...
…………………………………………………………………………………………………………. यो मुलुक सिंगापुर जस्तो बनिसकेको छैन मात्र राजनीतिक परिवर्तन...