1. A compound sentence contains two or more independent clauses joined by a coordinator. The structure of a compound sentence sends certain messages to readers. First, it tells readers that the sentence contains two ideas, each one deserving its own independent clause. Second, it tells readers that these two ideas are approximately equal in importance, since they are balanced as a pair.
A number multiplied by zero is zero, and a number multiplied by one is the same number.
Число, умноженное на ноль, равняется нулю, а число, умноженное на единицу, равно самому себе.
2. Compound sentences can be formed in three ways:
a) by using coordinating conjunctions (and, but, for, nor, or, so, yet) or a or by a set of correlatives (either-or, neither-nor, not only-but also, both-and). Except for very short sentences, coordinators are always preceded by a comma.
They may take our lives, but they will never take our freedom.
Они могут убить нас, но не могут забрать нашу свободу.
Not only do our parents encourage us to work hard, but also they reward us when we succeed.
Наши родители не только побуждают нас работать усердно, но и поощряют нас, когда мы добиваемся успеха.
b) by using the semicolon, either with or without conjunctive adverbs (also, besides, hence, for example, however, meanwhile, then, so, finally, as a result, earlier, that is, in fact, however, thus).