Exercise - Mixed Tenses B1 - B2 (5)

When we got to their house, we realised that they had been working on our project for hours.

We use the past perfect tense for an action or situation that took place before another action or situation in the past (we got to their house). Here: past perfect progressive, emphasising the duration of the action.

By the end of this month, all of the students will have completed the course.

We use the future perfect (will have completed) to talk about actions that will have been completed by a specific point in the future (by the end of this month).

Because of the earthquake the inhabitants have been living at different hotels since March.

A perfect tense is used for actions and situations that began in the past and continue into the present.

It is not the first time that he has lied to his friends.

It is (not) the first/second/etc. time is usually followed by the present perfect.

They will buy a present as soon as they have enough money.

In temporal clauses (introduced by as soon as, after, before …), we use a present tense to talk about the future (not the future simple).

Our train is due to depart in two hours.

Compare:

be due to → planned or scheduled events in the future

be about to / on the point of (+ -ing form) → be on the verge of

His sister graduated from university last summer.

A completed action in the past with a past time marker (last summer) → simple past

My father used to live in Japan when he was a child.

Do not confuse used to (habits or regular actions in the past) with be/get used to (to be accustomed to).

When we entered the room, everybody was talking about the accident.

An unfinished action in the past that is interrupted by a shorter action (we entered the room) → past progressive

Nobody could leave the park because someone had locked the gates.

We use the past perfect tense for an action or situation that took place before another action or situation in the past (nobody could leave).

I promise that I will help you next week.

Promises concerning the future are expressed in the future simple tense.

We have eaten in the new Chinese restaurant twice.

Experiences we had at some point in our life → present perfect