Which descriptions are correct about python's index? (Multiple Choice)

After the data has completed the feature engineering operation, in the process of constructing the model, which of the following options is not a step in the decision tree construction process?

In neural networks, weights are often shareD. Which of the following neural networks will share weights?

In the process of training the neural network, our goal is to keep the loss function reduced. Which of the following methods do we usually use to minimize the loss function?

What are the implementation modes of TensorFlow?