完成时态是英语中重要的一种时态，用于描述已完成的动作或事件，通常由“have/has + 过去分词”构成。常见的完成时态句型包括肯定句（如“I have finished my homework.”）、否定句（如“I haven't watched that movie yet.”）和疑问句（如“Have you completed this task?”）。掌握完成时态句型是学好英语的关键之一。
下面是一些常见的完成时态句型：
- 肯定句
- 我已经完成了作业。 I have finished my homework.
- 他已经去过中国了。 He has been to China.
- 我们已经讨论了这个问题。 We have discussed this issue.
- 否定句
- 我还没有看过那部电影。 I haven't watched that movie yet.
- 她还没有提交报告。 She hasn't submitted the report yet.
- 我们还没有决定去哪里旅游。 We haven't decided where to travel.
- 疑问句
- 你完成了这个任务吗？ Have you completed this task?
- 他已经做完作业了吗？ Has he finished his homework?
- 他们已经买了机票了吗？ Have they bought the plane tickets?
