All you need to remember in using the perfect tenses, you are dealing with two actions or time and the other one happened first before the other.Originally Posted by latoof
-used to indicate an action that happened in the past with out specifying the exact time.
Form: has / have + past participle (has / have eaten)
Peter: Have you eaten in that restaurant?
John : Yes, I have eaten there.
Peter: When did you eat there?
John : I ate there last Tuesday.
Note: In the sample sentence, notice the use of the present perfect tense (have eaten) and the simple past tense (ate). Simple Past was used because the exact time in the past was specified unlike in Present Perfect, it implies that the action happened in the past but the exact time was not mentioned.
- deals with two action that both happened in the past but the other action
happened first before the other.
Form: had + past participle (had eaten)
a.) John had eaten when Peter arrived.
b.) John ate when Peter arrived.
Note: Notice the difference of the two sample sentences. In the first sentence, John had already completly finished his eating when Peter arrived. However, in the second sentence, John only ate after Peter arrived. Use the past perfect tense to clearly specify which of the action happened first when using the connectives "when" and "by the time".