Conditional Sentence Type I refers to a future condition in the main clause and present tense in the subordinate clause. The event in the main clause will occur if the condition in the subordinate clause is met. Conditional Sentence Type II refers to a present condition and is used to describe a present or current event that will occur if the condition in the subordinate clause is different. Conditional Sentence Type III refers to a past condition in the main clause and past tense in the subordinate clause, describing a past desire that could not be realized.