I (suppose) she is not yet thirty years old.

问题补充：

I (suppose) she is not yet thirty years old.

答案：

我猜想她还不到三十岁.suppose作vt动词时是假设假想虚拟语气,做vi词是是猜想之意,句中直接跟宾语重句是vi词性后面省略that一词I (suppose)（that） she is not yet thirty years old.

======以下答案可供参考======

供参考答案1:

我觉得她可能不到30岁，

供参考答案2:

Suppos是猜测，代表了＂我＂的观点。

供参考答案3:

我觉得她还不到30岁呢