例句：
-It seems that you know much about the film．
-That's true．I have seen it several times．
--看来你对这部电影很了解．
--这是真的．我已经看过好多遍了．
根据 several times，可知在这里的意思是好多次了，所以我对这部电影很了解，一般情况下，如果句子中含有短语several times，这个句子所使用的时态应该是现在完成时，它的构成是：have/has+动词过去分词．
例句：
In this experiment， they are wakened several times during the night， and asked to report what they have just been dreaming .
句中已给出频次状语several times，说明要用完成时态，同时句子的时态定位是现在时they are wakened，显然不能用过去完成时