Questions

Computer was invented by Charles Babbage.

The First Mechanical Computer Designed by Charles Babbage, a British mathematician was called as Analytical Engine which resembles today's modern machines  between 1833 and 1871.

The modal ‘Could’ is used to express possibility. It is simply used to state one or more things that are possible or were possible in the past. In this statement, ‘to have achieved’ needs to be replaced with ‘for achieving’ to make the sentence correct. Thus, the correct sentence would be, ‘When I finished writing the letter, I could not help admiring myself for achieving the impossible’.

The Indus Valley Civilization was Non-Aryan because it was Urban.

Harappan Civilization is also known as The Indus Valley Civilisation. It was a Bronze Age civilisation mainly in the northwestern regions of South Asia, extending from what today is northeast Afghanistan to Pakistan and northwest India.