外教问我有不明白的吗，我指着书上的某个单词想说“这里不懂"，怎么翻译“这里不懂”。

直接指着说here就好了，或者how about this point ?

I don't understand this one

Please explain it for me,thank you.

。
一般翻译没得直接意思的，就可以采取意思相近的词语来翻译~~

I don't understand this。

如果有序号的话，就说：I don't understand number 1, 2, 3, 等等类似