the sum of two numbers is 30. The diffrence of the two numbers is 4. What is the lesser number

Building Environmentally-friendly Houses 

Most people think of a greenhouse as a special glass structure used to grow plants all year long. 
Now there is another definition. A “green house” is the result of a movement to produce houses 
that are less harmful to the environment than other houses. 
Recent films, books, magazines and newspapers have reported serio

Je dois trouver la particularité grammaticale de la phrase : Des millions d'enfants exploites. J'ai pensé que c'était le mot million,mais je n'en suis pas sure et je ne sais pas comment l'expliquer

qui sont les principaux chevaliers de la table ronde ?