【单选题】Viruses 1. contain both protein and nucleic acid. 2. infect all domains of life. 3. can grow in the absence of living cells. 4. are generally the same size as prokaryotes. 5. always kill the cells the...
【单选题】It is generally believed that the main reason for the formation of acid rain in China is that ( ) and other acidic gases enter the atmosphere and gradually form acidic precipitation with PH < 5 and 6.