Answer 1

1-https://beginnersbook.com/2013/05/java-multiple-inheritance/
2-https://www.sololearn.com/Discuss/1144361/how-can-you-justify-that-multiple-inheritance-will-be-possible-with-the-help-of-interfaces
3-http://www.instanceofjava.com/2014/12/why-java-does-not-supports-multiple.html