Exercise 17. Use the verb in brackets in either Perfect Simple or Perfect Continuous form.
1. He (not to work) very well recently. 2. He (not to work) for years. 3. I (to learn) irregular verbs all afternoon. 4. I (to learn) irregular verbs – ask me any. 5. I am tired – I (to calculate) our expenses all day. 6. I (to calculate) our expenses – we spend too much on clothes. 7. Sorry about the mess - the workers (to install) new computers in my office. 8. The workers (to install) new computers and we can start working now. 9. They (to monitor) the situation since the elections started. 10. They (to monitor) the situation – here is their report.
* Compare the use of Present Perfect and Past Indefinite:
e.g. We have just seen them (a past action which time is not definite) –Present Perfect.
We saw them last week (a past action, completed at a definite time in the past) –Past Indefinite.