In Chinese language teaching as a foreign language, one of the important but difficult points for the overseas students who attend to school to study Mandarin is the potential complement. Therefore, many relevant mistakes are often made by them in the process of learning. For example, they usually use the potential component in the situation that it is not allowed to use. For instance, the sentence我已经走得了了，让我出院吧 is incorrect because 能should be applied to indicate the recovery of ability but not the potential complement. Therefore, it should be replaced as我已经能走了….

When we intend to express that there is no possibility of implementing certain act, we should use the pattern verb + 得/不 + 了. When we want to indicate certain act is not allowed, we can’t use verb + 得/不 + 了, but use 不能 + verb. Since the sentence we just mentioned indicates do not allow doing something, it is not correct to use the potential complement.

The second mistake the foreign students often make is wrong order. Let’s take the sentence 我怎么学也不学会as an example which is incorrect. If you want to express whether there is ability or possibility of realizing certain thing, you should use the potential complement. As a result, 不should be placed between the verb and the complement, but not before the verb. Therefore, this sentence should be 我怎么学也学不会. If you want to express the thing is not realized objectively, you are suggested to use the pattern 没 + verb + complement of result.

After a period of time learning, the overseas students who study in intensive Mandarin course in China may know 来and去in the sentence with serial verb phrases like 来/去 + verb are not the verbs indicating the main act, but only indicate the tendency of the act after them and lead in the act. In other words, the act expressed after 来and去are the main point. Therefore, it is recommended to use 能/不能 + 来/去 + verb if you intend to emphasize whether the main act will be realized or not like 你能不能去旅游？我不能去旅游了.