this week是时间段,一般情况下this week只是表示一个时间,它要用什么时态根据句子需要的时态而定.we finished the task this week.we will finish the task this week.
要用于现在完成时中一般用于下面的结构：
表示动作从过去某一时刻开始一直延续到现在：has/have been +doing 与all the time,this week,this year,all day,since+从句,for```连用.
we have been working for the task this week.这个星期我们一直在做这个项目.
we have been working for a week.
we have finished the task this week.这个句子有点不合理,一般现在完成时后面跟的应该是时间点,since+时间点,或者直接用we have finished the task 表示动作已经完成了,且对现在有影响,是可以直接用现在完成时的.