【正文】
d by environment. [B] happiness and unhappiness are mutually conditional. [C] unhappiness is subject to external more than internal factors. [D] happiness is an uncontrollable subjective feeling. 2. The author argues that one can achieve happiness by [A] maintaining it at an average level. [B] escaping miserable occurrences in life. [C] pursuing it with one’s painstaking effort. [D] realizing its coexistence with unhappiness. 3. The phrase “To date” (Para. 4) can be best replaced by [A] As a result. [B] In addition. [C] At present. [D] Until now. 4.