原文載於蘇聯教師報,由贾同志全文譯出。就我們的篇幅說來,譯文是過長了,我們在保留原意的原则下,作了些修改。小標題也是我們加的。關於這方面的新理論,科學通報三卷四期有詳細的文字介紹請參閱。 The original article was published in the Soviet Union Teacher’s Paper and was translated by Jia Tongzhi. For our space, the translation is too long. We have made some changes under the principle of retaining the original meaning. The subtitle is also what we added. With regard to the new theory in this area, please refer to the detailed introduction of the scientific circular in the third volume and the fourth period.