Problems encountered in America

1. study problems

1.1. insufficient English ability

1.1.1. take more time to understand materials

1.1.1.1. take more time to finish assaies

1.1.1.1.1. no time to study English

1.1.2. cannot catch up with professors, dare not to ask questions in class

1.1.3. lack of the ability communicating with foreign classmates

1.2. insufficient self-control

1.2.1. cannot focus on assay for a long time