After-class assignment : Identify the research subject (subject matter), research object (content) and research method if it is included from the following titles (16 分) 1.One-step inactivation of chromosomal genes in Escherichia coli K-12 using PCR products 2. Ecological responses to recent climate change 3. Technical advantages of improving mine ventilation by the double-stopping method 4. Long-range mutual synchronization of spin Hall nana-oscillators