Besides the problem of the "high mobility" of foreign instructors, due to differences in language and culture, they are often incapable of conducting a class on their own and need an assistant to maintain order or explain difficult vocabulary.
除了流動性高，由於語言、文化的不同，外師常無法獨立上課，需要助教在旁維持秩序或解釋難懂的詞彙。