but sometimes he still has some trouble speaking Chinese.語法結構？speaking是動名詞？是不是等于to speak Chinese.

熱心網友

在這個句子中實際是省略了trouble后面的介詞in,have trouble (in) doing sth.這是固定的搭配,意思做某事有困難,故而此處的speaking并不等于to speak Chinese.

熱心網友

have trouble (in) doing sth. in可以省略這里speaking Chinese不等于to speak Chinese

熱心網友

have trouble (in) doing sth. 固定搭配