The first two stages in the development of civilized man were probably the invention of weapons and the discovery of fire, although nobody knows exactly when he acquired the use of the ______.

A. adopted B. incorporated
C. administered D. established

As I began to explain my ideas, he asked me to write the equations on the blackboard so he could see how they developed. Then came the staggering — and altogether endearing — (39) . "Please go slowly. I do not understand things quickly." This was from Einstein! He said it gently, and I laughed. From then on, all (40) of fear were gone.