3中解法：

1. df[][]
2. df.loc[][]
3. df.query().

import pandas as pd

Nowcoder = pd.read_csv("Nowcoder.csv", sep=",")

# res = Nowcoder[Nowcoder["Num_of_exercise"] >= 10]["Level"].median()

res = Nowcoder.loc[Nowcoder["Num_of_exercise"] >= 10]["Level"].median()

print(int(res))

# print(Nowcoder.query("Num_of_exercise >= 10").Level.median().astype("int"))