This is ______I wanted. A the one what B which C one which D the one

完整的是 This is the one that I wanted

先行詞是the one 後面是由that 引導的定語從句，修飾the one

而that在定語從句中，是充當want的賓語，是賓語成分，可以省略掉，所以就變成 this is the one I wanted

如果用A,應該是 This is what I wanted. what引導的壹個表語從句

5. B /

as we know, I think, to be honest 等很多詞組都是插入語，它們對原來的句子沒有影響

這裏as we know是插入語，可以把它忽略掉，那剩下的就是 Oxford is one of the best...... 這是壹個完整句子了。