Question

助动词与一般动词的区别在于它不充当什么成分而充当什么成分？

Answer 1

一般动词可以在句子中担任谓语，而助动词不行。助动词，顾名思义，是帮助实意动词的，它的作用是帮助动词构成疑问句，否定句或时态，语态。
常用的助动词有 do,be, have, 和will, shall等，在使用时，要根据情况作人称和时态的变化。如：
1. Do you like sports and does your brother like sports?

I didn't go to the meeting last week.
注：助动词do/does/ did 帮助动词构成疑问句，否定句。
2. Li Ming has finished his homework and is playing computer games.
注：助动词has 和is 分别帮助动词构成时态（完成时和进行时）
The kids will have a spring outing tomorrow.
注：助动词will 帮助动词构成时态（一般将来时）
3. He was very happy as he was praised by his teacher for his progress.
注：第一个was 是系动词，与happy一起构成复合谓语；第二个was是助动词，与过去分词 praised一起构成被动语态。