1 - By the time a child reaches school age he ought to be able to dress himself fairly quickly.

2 - The political theory of socialism, which gave rise to communism, had been around for hundreds of years by the time a German philosopher named Karl Marx put pen to paper.

3 - By the time the American colonists took up arms against Great Britain in order to secure their independence, the institution of Black slavery was deeply entrenched.

4 - While only one in 10 male engineers leave their field by the time they reach their 30s, about one in four women are not working in engineering despite having completed the necessary education.

5 - By the time newcomers to the United States had passed through the immigration center on Ellis Island, they had been screened for certain contagious diseases.