Is doctor a concrete noun or abstract noun

1+1=4

Explanation:

because when you add the 2 ones together than you get 4 for example if timmy has 1 apple and his friend gave him 1 apple then he has 4 apples

answer: i dont know

explanation:

unyuoinjk

kn,khftdctfjvgkbhlnjmk,l; jnhgbfdcsedrftgyuij; okpl'iuytredtwsdeyrfuijkol'

[olp

the correct answer is the following is a list of inventions made in the medieval islamic world, especially during the "islamic golden age" (8th to 13th centuries),[1][2] as well as the late medieval period, especially in the emirate of granada and the ottoman empire.

science and technology in the islamic world adopted and preserved knowledge and technologies from contemporary and earlier civilizations, including persia, india, china, and greece-roman antiquity, while making a number of improvements and innovations.