What environmental factor in the second millennium bce led the Xiongnu and other central Asian nomads to spread southward into settled areas?  

  Which of the following is generally true of the impact of the empires of Alexander and the Mauryan kings?  

  Which of the following was an important social change during the Warring States period in China?  

  Why was camel domestication important to overland trade in the first millennium bce?  

  How did the wealthy elite respond to the changing economy after Alexander’s conquests and the rise of Rome?  

  By the third century bce, the Xiongnu used their superior bronze technology to become the dominant nomadic group in the eastern steppes.  

Bonus Question (5 points) The above figure is for the gradient boosting algorithm for regression. Step 1. A new decision tree (DT) is trained with feature X and label r (i.e., residual) to predict the residual. Step 2. The predicted residual in Step 1 is multiplied by the learning rate and is added to the prior predicted The learning rate is between 0 and 1 for slow learning to avoid overfitting. Step 3. The residual is updated by subtracting the new DT in Step 1 multiplied by the learning rate. Step 4. The final predicted Y in the gradient boosting is the additive function of DTs multiplied by the learning       rate in each stage. Overall, gradient boosting is a (1) _____________ (a. parallel learning, b. sequential learning; 1 point). In addition, a new decision tree in each stage is created based on the information from the prior trees to improve performance. Based on the algorithm, which one is not a hyperparameter for gradient boosting? (2)_________ (2 points) the number of trees the maximum depth of each tree learning rate dropout rate the number of splits in each tree

  Zhou rulers created a theocracy, similar to states in Southwest Asia.  

  Which of the following characterizes the Rosetta Stone’s significance?  

  What are the two major Sanskrit poems of ancient India?