现在完成时结构、用法、标志词

现在完成时 过去不确定的时间里发生的动作对现在造成的影响或过去的动作一直持续到现在并有可能继续持续下去。 结构：主语 + have/ has + 过去分词 否定形式：主语 + have/ has not + 过去分词 疑问形式： Have/ Has+主语+过去分词 I had a big dinner with my friends. I watched a wonderful film. I read an interesting book. I have just seen it. Have you seen it? I haven't seen it. 常用在现完中的时间状语 ①already 已经 肯定句中或句尾   例: I have already found my pen. = I have found my pen already. ②yet已经  否定句和疑问句句尾  例：I have not finished the work yet. Have you bought a computer yet? ③ever曾经 句中                 例：Have you ever seen pandas? ④never从不   句中            例：I have never been to Beijing. ⑤just刚刚 句中                 例：I have just done my work. ⑥before以前     句尾            例：I have never been there before. ⑦so far到目前为止                 例：So far he has learnt 200 words. ⑧次数                          例：I have been to Beijing ten times. ⑨for+时间段 例：Jim has lived here for 2 months. ⑩since+过去时间点 例：Lucy has been here since 1990. since+时间段+ago 例：Lucy has been here since 3 years ago. since+过去时的句子 例：Lucy has been here since she came here.