The only thing that can stop you is you.
实际发展水平与潜在发展水平之间的距离,前者由独立解决问题决定,后者由在成人指导下或与更有能力的同伴合作解决问题决定。
Concerning the gods, I have no means of knowing whether they exist or not or of what sort they may be. Many things prevent knowledge including the obscurity of the subject and the brevity of human life.