Fill in the blanks in the sentences using the zero conditional, providing the correct verb tenses.

Here's the completed exercise with explanations: 1) If I **eat** too much, I always **have** a stomach ache. * **Explanation:** In zero conditional sentences, we use the present simple tense in both the 'if' clause and the main clause. The 'if' clause describes the condition (eating too much), and the main clause describes the result (having a stomach ache). Both are general truths. 2) When it **snows**, the landscape **becomes** white. * **Explanation:** Similar to the first sentence, we use the present simple in both parts of the sentence to describe a general truth. 'When' can be used interchangeably with 'if' in zero conditionals. 3) Mike always **tells** me the same when he **is** in trouble. * **Explanation:** Again, we use the present simple in both clauses because this is a habitual action or a general truth about Mike's behavior. 4) If I **do not sleep** 7 hours at least, I **have** problems to wake up. * **Explanation:** Using the present simple negative ('do not sleep') and present simple ('have') to express a condition and its result. This describes a common situation or a general truth for the speaker.