【简答题】How is a blue hole different from a cave? a. A blue hole is always underwater. b. Caves usually have two sinkholes. c. Caves are inland, but blue holes are not. 2. What makes blue holes ...
【单选题】Synthetic biology provides technical support for reviving and constructing from scratch dangerous bacteria or viruses such as Ebola, Smallpox and SARS viruses that can kill people in mass easily; this...