Here are my evaluations of the example thesis statements:
1. This is a good thesis statement. It clearly identifies the topic (whether mathematics can replace human languages) and presents the writer's point/opinion (that it will be explored) in a focused way.
2. This is a good thesis statement. It identifies the topic (long distance relationships) and presents the writer's opinion (that they are not impossible despite a common myth) in a clear, focused statement.
3. This is a good thesis statement. It identifies the topic (genetically modified food production) and presents the writer's opinion (that it should not be encouraged due to health and ethical concerns) in a focused statement.
4. This