【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 ...
【多选题】Reading the following passage and choose the correct answer(s). Six children were very sick in the hospital and Dr. Bessor, an expert on strange illnesses, was called to find the cause of the illness....
【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...