A young father was visiting an old neighbor. They were standing in the old man’s garden, and talking about children. The young man said,“How strict should parents be with their children?”
　  The old man pointed to（指着）a string (细绳) between a big strong tree and a thin young one.
　 “Please untie (解开) that string.” said the old man. “But first pull the string tight so that（以便于）the young tree is straight again.” The young man did so. He untied the string and only found that the young tree bent（弯）over to one side.
　 Then the old man said,“There, it is the same with children. You must be strict with them. But sometimes you must untie the string to see how they are getting on. If they are not yet able to stand alone，you must tie the string tight again. But when you find that they are ready to stand alone，you can take the string away.”

①浆细胞比效应T细胞含有较多的高尔基体和内质网；

②与硝化细菌最主要的区别是酵母菌有成形的细胞核；

③大肠杆菌细胞分裂前期时，每个细胞中含有两个中心体；

④神经干细胞分化成各种神经细胞的过程表现了细胞的全能性；

⑤将融合的异种植物花粉育成幼苗并用秋水仙素处理可得到可育植株；

⑥高等动物剧烈运动时肌肉细胞因供氧不足而进行的无氧呼吸不产生CO₂

第一次国共合作的政治基础新三民主义适应了时代潮流的精神，集中体现在