(3a) I came upon an old classmate when I went to town yesterday.
(3b) When I went to town yesterday, I came upon an old classmate.
(4a) Steel is commonly used to make knives, razors and other useful tools because of its durability.
(4b) Beacuse of its durability, steel is commonly used to make knives,razers and other useful tools.
(5a) I was delighted and amused by the classical opera
(5b) I was amused and delighted by the classical opera.
(6a) That singers life was tragic and brief.
(6b) That singers life was brief and tragic. 4. 把句子中一系列的项目作逻辑性的排列。例如：
(7) Tony ate his dinner, watched TV, and then went to bed.
(8) Were you bored with years of study in elementary school, high school and institute of higher education? 5. 必要时，重复重要的语词或概念。
(9) Jackie enjoys the company of ladies. He likes their beauty, he likes their delicacy, he likes their vivacity, and he likes their silence.
(10) ...the land stretched out without names. Nameless headlands split the surf； nameless lakes reflected the  ；nameless mountains and nameless rivers flowed through nameless valleys and nameless bays.
(11a) A pedestrian was struck on the head by a flying stone.
(11b) A flying stone struck a pedestrian on the head.
(12) Seven dwarfs lived here in the centre of the dark forest. → Here, in the centre of the dark forest lived seven dwarfs.