As for the RandomForestClassifier issue @MrHuanwang, your implementation of Ex 10 has a flaw in it.
If you look at your assignment, you’ll notice you are using RandomForestClassifier (when setting up the estimator variable) in your Ex 10, before it is actually imported later (for the very first time in the assignment) in the test cell of Ex 10. So essentially, you are using a hard-coded function, that too before it is defined. You can get away with that behaviour in a Jupyter Notebook, but not when it would come to the grader.
If you read the description for the parameters for the function in Ex 10, you’ll realise what needs to be used to set up estimator.
Hope this helps,
Mubsi