The key answer of exercise 1

PRESENT PERFECT

FORM

Affirmative

• I / You / We / They've (have) cleaned,
• He / She / It's (has) cleaned.

Negative

• I / You / We / They haven't (have not) cleaned.
• He / She / It hasn't (has not) cleaned.

Interrogative

• Have I / you / we / they cleaned?
• Has he / she / it cleaned?

Short answers

• Yes, he / she / it has.
• No, you / we / they haven't.

USE

Actions that happened at an unspecified time in the past when the emphasis is on the action rather than on the time.

Example:

• We have hoovered the living room.

To give generic information about things that have happened recently.

Example:

• She has read a new book.

Actions that have happened recently when the result is important in the present.

Example:

• I have won the lottery!

Actions occurring in a period of time that is not yet finished.

Example:

• We haven't worked much this week.

To talk about experiences that we have had in our lives until now.

Example:

• I have traveled to Europe.

To talk about how many times a person has had a certain experience or about the duration of an activity.

Example:

• They have visited the museum three times.

SIGNAL WORDS

• Ever and never.
• Just, already, yet and still.
• Lately, recently, so far, up to now, today, in the last few days, before, almost, nearly.
• Always, often, rarely, seldom.
• Today, this week / month / year.
• Once, twice, three / many times.
• It's the first / second time.

PAST SIMPLE

Actions that took place at a specific time in the past and can be considered completed.

Example:

• Last week he bought a new sofa.
• She finished her project yesterday.
• They went to the beach last summer.
• Last month, she traveled to Japan.

Actions that are definitively in the past, even if they are recent.

Example:

• He arrived 10 minutes ago.
• She cooked dinner an hour ago.
• We watched a movie last night.
• Five minutes ago, they started their meeting.

SIGNAL WORDS

• Yesterday.
• One, two days ago.
• Last week / month / year