When COVID-19 pandemic is rampant all over the world, to ensure the safety of students and staff, colleges and universities have adopted the teaching methods of online teaching and online examination. For students who have not been studying abroad for a long time, they just adapted to the rhythm of their study abroad life and were disrupted by this sudden disaster. During the long period of class suspension, students all over the world must study at home. Different schools have different requirements. Some only need to complete online exercises of various subjects every day, some need to follow the progress of learning, watch the teacher's online explanation clips, and then complete the relevant homework. We can find that most students have never studied at home, so many students will not adapt to this learning method. Currently, it is very important to study at home efficiently. If the learning efficiency at home is very poor, it is very likely to lead to the decline of students' performance.
