join, combine, connect, associate, link 与 unite 这些词都有“连接”、“联合”的意思。

(1) join指把原来分离着的、本无关联的东西紧密地连接在一起，但仍可分开；或指把分散的人或组织通过共同的行动而联合起来，或加入某团体中去。

• He joined the two ends of the rope together in a knot.
  他把绳子两头打个结连了起来。
• We haven't got enough money, and have to join in with our relatives to buy that house.
  我们没有足够的钱，只得与亲戚们共同出资买下那所房子。
• I will never forget the day when I joined the Party.
  我永远也忘不了入党的那一天。

(2) combine指两个或两个以上的人、组织或物结合在一起，结合后个体被忽略，强调整体性。

• A sense of common danger combined them in operations of defence.
  共同的危险感使他们联合起来进行防卫战。
• The two old schools are to combine to form one big new school.
  这两所老学校要合并成一所规模大的新学校。
• One atom of carbon combines with two atoms of oxygen to form a molecule of carbon dioxide.
  一个碳原子和两个氧原子化合而生成一个二氧化碳分子。

(3) connect指两事物在某一点上相连接，或以某种媒介把两个相关联的事物连接起来，所连接的事物具有相对的独立性。

• This corridor connects with the living room.
  这走廊与客厅相连接。
• The bridge connects the island with/to the mainland.
  这座桥把这个岛屿与大陆连接起来。

(4) associate主要指在思想上把某事物与其他事物联系在一起；在表示人与人之间的联系时，指相互平等的关系。

• We naturally associate the name of Darwin with the doctrine of evolution.
  我们在思想上很自然地把达尔文的名字和进化论联系在一起。
• We associate Egypt with the Nile.
  说到埃及我们就联想起尼罗河。
• They were closely associated with each other during the war.
  在战争期间，他们的关系很密切。
• He associated himself with Mr. Gray in the company.
  他和格雷先生是公司同事/共同经营者。

(5) link指比connect更巩固的连接，暗指各事物间连接的牢固性或不可分割性。

• Wages are linked to prices in a number of countries.
  在一些国家，工资是与物价挂钩的。
• The interest of individuals is always linked with those of the country.
  个人利益总是同国家利益联系在一起。

(6) unite指个人或不同的组织为了共同的目标而联合起来而形成新的整体，强调团结性和统一性。

• United as one, the people of that country waged a just war against aggression.
  那个国家的人民团结一心，进行了反侵略的正义战争。
• The retailers united against the department store.
  零售商团结起来对抗那家百货公司。