In music, which term (from the italian word for "happy") means that you should play a piece at a quick tempo?

Allegro is a term which refers to music and which means you should play a piece at a quick tempo ad the word means happy.
There are many Italian terms which are used in music to explain or to show the speed or tempo of the music. Most of the terms in music are Italian because many important composers of early period were Italian.

To form soil, the two processes which must occur are erosion and weathering, so the correct answer is "soil formation is a continuous presses, but also one which takes a long time, it can sometimes take more than five hundred years for 1cm of soil to form.