This document discusses different types of conditional sentences in English. Type 0 conditionals express general truths using the simple present tense in both clauses, such as "If you heat water to 100C, it boils." Type 1 conditionals express possible future events, using the simple present in the if-clause and will/can/may + verb in the main clause, like "If it rains tomorrow, we can't go to the park." Several example sentences are provided to illustrate each type of conditional.