句子是由詞或短語按文法規則組成，表達一個完整意思的語言單位。好的英語句子應該是結構意思正確完整，連貫流暢，言簡意賅。但是如果一篇文章中所有的句子都是結構單一(以主語開頭，採用"主-謂-賓"或"主-謂-表"的結構)、長短均等的話，句子寫得再好，文章也是單調呆板，缺乏生氣。要克服這種句式"單一"現象，可以通過變換句子開頭以及句式兩種手段。
一、句子開頭多樣化
寫作時最常見的是用名詞或代詞構成的主語作為句子的開頭。除了主語外，句子中還有以下幾種成分可以作為句子的開頭。
1.以同位語作為句子的開頭。試比較下列兩個句子：
A. Xiao Wang, our monitor，will attend the meeting.
B. Our monitor, Xiao Wang, will attend the meeting.
句A以主語Xiao Wang開頭，句B以同位語Our monitor開頭。
2.以單個修飾語作為句子的開頭。
這個修飾語可以是形容詞、分詞或副詞。試比較下面幾組句子：
A. She is young and ambitious, she works hard to get the job.
B. Young and ambitious, she works hard to get the job.
句A以主語She開頭，句B以形容詞短語Young and ambitious開頭。
C. The girl entered the room gracefully.
D. Gracefully, the girl entered the room.
句C以主語The girl開頭，句D以副詞Gracefully開頭。
E. The students reached the top of the mountain exhausted.
F. Exhausted, the students reached the top of the mountain.
句E以主語The students開頭，句F以過去分詞Exhausted開頭。
3.以短語修飾語作為句子的開頭。
短語修飾語可以是介詞短語、不定式短語、分詞短語以及獨立主格結構。試比較下列各組句子：
A. A beautiful girl stood in front of me.
B. In front of me stood a beautiful girl.
句A以主語A beautiful girl開頭，句B以介詞短語In front of開頭。
C. The students worked hard to pass the exam.
D. To pass the exam, the students worked hard.
句C以主語The students開頭，句D以不定式短語To pass the exam開頭。
E. He was confused about the problem and went to ask for his teacher.
F. Confused about the problem, he went to ask for his teacher.
句E以主語He開頭，句F以過去分詞短語Confused about開頭。
G. You may go home after you finish your homework.
H. Your homework finished, you may go home.
句G以主語You開頭，句H以獨立主格結構Your homework finished開頭。
4.用從句作為句子的開始。試比較下列句子：
A. I will attend your lecture if I am free.
B. If I am free, I will attend your lecture.
C. We all know she is famous.
D. That she is famous is known to us all.
句A和句C以主語開始，句B和句D以從句開始。
值得註意的是句子的開頭與句子所需強調的意義密切相關。改變詞序有時會導致句子意義的細微變化。因此，在特定的上下文中決定是否改變某一句子的詞序時，不僅要考慮我們所要表達的意思(如為了強調句子中的某個成分，將正常語序中較晚出現的成分移到句首)，還要考慮是否有利于上下文的銜接過渡以及句子是否均衡等。