The complex sentence. The compound sentence

A complex sentence consists of two or more simple sentences, each with its own grammatical base. If the parts are joined by a conjunction the sentence is «союзное»; if they are joined only by intonation it is «бессоюзное». Conjunctive sentences are of two kinds: «сложносочинённое» («ССП», compound) and «сложноподчинённое» («СПП», with a subordinate clause). In an «ССП» the parts do not depend on each other and are joined by coordinating conjunctions: joining («и, да, ни … ни, тоже, также»), opposing («а, но, да, однако, зато, же») and separating («или, либо, то … то, не то … не то»). The parts are usually separated by a comma: «Матч начался вовремя, и стадион замер». «А» shows a difference, «но» a mismatch; «зато» is used in a positive situation, «однако» in a neutral or negative one. An «ССП» must be told from a simple sentence with homogeneous predicates: «Дети играли во дворе и смеялись» — one subject, simple sentence, no comma; «Дети играли во дворе, и соседи улыбались» — two bases, with a comma. If the parts share a secondary part or a common subordinate clause, there is no comma before «и»: «В лесу стемнело и стало прохладно».