Degree: 太…了, 真, 非常, 最

The rule 太 + adjective + 了 is a fixed frame and nearly always keeps all three parts: 太好了！
真 + adjective needs no 了: 真好！ 你的汉语真好。
非常 is stronger than 很 and takes no 了 either: 非常好吃。
最 = most, immediately before the adjective: 我最喜欢这本书。