Not one of 和not the only one of 的定语从句中动词用法？

(not ) one of 后面接复数名词，如后加定语从句，一定修饰这个复数名词。如: He is (not) one of the students who have been to the Great Wall. 他(不)是去过长城的学生中一个。
而(not) the only one of后面也接复数名词，但后面的定语从句一定修饰the only one。如: He is (not) the only one of the students who has been to the Great Wall. 他(不)是这些学生中唯一一个去过长城的人。

前者先行词是of后面的名词 ，所以定语从句中的谓语与of后面的名词复数一致。
后者先行词是the only one，所以定语从句中的谓语 应该用单数形式。
如he is not one of the students who are never late。他不是从不迟到的学生中的一个。
he is not the only one of the students who is never late.他不是那些学生中唯一不迟到的学生。

one of+复数名词时，谓语动词用复数，the only one of+复数名词时，谓语动词用单数。这是固定的，结合语境理解记忆。