1, bear and tiger cross the river, and then bear goes back.

2. The bear and the lion cross the river, and the bear goes back.

3. The big lion and the big tiger cross the river.

4. Little bear and big bear cross the river

Logical reasoning is deductive reasoning;

It is a process of drawing specific statements or individual conclusions from the general premise through deduction, that is, "deduction". The logical form of deductive reasoning is of great significance to rationality because it plays an irreplaceable role in correcting the rigor and consistency of human thinking. Logical reasoning includes deduction, induction and review.