如果天气允许的话，我们明天去划船。
If weather permits, we'll go boating tomorrow。(一般表达法)
(if引起条件状语从句，修饰动词go。)
Weather permitting， we'll go boating tomorrow。(高档表达法)
(含有逻辑主语的现在分词短语称作独立主格结构，在句中做状语，修饰动词go。)
司机驾车撞人之后逃之夭夭，只留下被撞的老人倒在路上。
The driver escaped without stopping；he left but the old man was lying on the road。(一般表达法)
(分号两侧的两个句子相当于并列句，后句又是一个由but连接的并列句。)
The driver escaped without stopping, leaving the old man lying on the road。(高档表达法)
(并列句的次要分句可以在不用连词的情况下转为非谓语动词短语，做伴随情况状语，leaving表示主动含义，与前面的动作escaped相对同时发生，后面的并列句在不同的情况下，保留lying，担当old man的宾语补足语。)
我兄弟骑着车，车后座上驮着我。
My brother was riding the bike and I sat on the seat behind him。
(一般表达法)
(and连接并列句。)
My brother was riding the bike，with me sitting on the seat behind him。(高档表达法)
(with引起的介词短语替代原来的并列句，表示伴随情况。)