What is the problem with these five incorrect sentences? Thank you!

1. Water is the source of life, the basis of production, and the foundation of ecology. It is related to economic security and national security. Therefore, our country strives to fundamentally reverse the current situation of obvious lag in water conservancy construction.

2. China has become a major exporter of aquatic products. The high density, variety and low intensity of its seawater and freshwater aquaculture have led to frequent outbreaks of aquaculture diseases.

3. The current situation of Chinese handwriting of Chinese characters is not optimistic. Typos are increasing day by day. Many people believe that this is due to the widespread use of computers and mobile phones and the weakness of calligraphy education in schools.

4. China’s golden flower Li Na will usher in her first career Grand Slam final today. At a press conference after training at Melbourne Park yesterday, Li Na said she was very relaxed about the final.

5. Fei Xiaotong is a well-deserved event-oriented scholar and a representative of contemporary Chinese strategic intellectuals. He created two classics, "Jiangcun Economy" and "Rural China".