forge

Compared meaning: to give something a particular shape (verb).

比较义项：塑造，使某物具有特定形状（动词）。

• form

  Form describes parts, people, or ideas coming together into a shape or structure; it rarely means physically working a material by hand, and often appears with abstract nouns like opinion, plan, or habit.

  form 通常指若干部分、人或想法聚合在一起形成某种形状或结构，很少指用手直接加工某种材料，常与“意见、计划、习惯”等抽象名词搭配使用。

  The students formed a straight line outside the classroom door.

  学生们在教室门外排成了一条直线。

• shape

  Shape is the general, everyday word for giving any material or idea a particular form, including hard materials like wood or stone that cannot be poured or pressed into a mold.

  shape 是最通用、日常的词，可用来表示把任何材料或想法塑造成某种形态，即便是木头、石头这类不能倒入模具或按压成形的坚硬材料，也能用 shape。

  He used a small knife to shape the piece of wood.

  他用一把小刀把这块木头削出了形状。

• forge 本词

  Forge is a technical, narrower word: it specifically means to shape metal by heating it and hammering it, so it cannot replace the others for soft or non-metal materials.

  forge 是较专业、范围更窄的词，专指通过加热金属再锤打使其成形，不能用来加工柔软材料或非金属材料。

  The blacksmith forged a horseshoe from a glowing iron bar.

  铁匠把烧红的铁条打制成了一个马蹄铁。

• mold

  Mold implies pressing or pouring a soft, flexible material into or against a fixed pattern, or shaping someone's character over time through repeated influence.

  mold 表示把柔软、可塑的材料压入或倒入固定的模具中塑形，也可以指通过长期反复的影响来塑造一个人的性格。

  She pressed and molded the warm wax into a small heart.

  她把温热的蜡按压塑成了一个小心形。

All four mean to shape something. Form means parts or ideas joining into a structure. Shape is the general word for any material. Forge means to shape metal by hammering it hot. Mold means to press soft material into a pattern, or shape someone's character.

这几个词都表示“使某物具有特定的形状或形态”，但所用材料、方式和语气有所不同，容易被中国学习者混淆。这里不比较 form 作名词表示“表格”的用法，也不比较 forge 表示“伪造”的义项。