1) the local community of collingwood in 2) … sydney is abuzz with news of 3) … unusual humming sound coming from 4) … preston park. 5) … sound was first noticed by 6) … group of children who were playing 7) … football at 8) … park. as one of 9) … children said: "it was 10) … strangest thing i've ever heard, it sounded like someone humming 11) … song really, really loudly." later in the same week, more visitors to 12) … park heard 13) … mysterious sound. eventually, the police was called upon to investigate 14) … matter. by now, the strange hum had become extremely loud and could be heard all over 15) … area. "sometimes it's worse at 16) … night, 'said mrs jacobs, 17) … local resident. later in 18) … … week, 19) … … team of scientists will come to collingwood in 20) … effort to solve 21) … mystery of the humming noise.

The PRESENT PERFECT TENSE is formed with a present tense form of "to have" plus the past participle of the verb (which can be either regular or irregular in form). This tense indicates either that an action was completed (finished or "perfected") at some point in the past or that the action extends to the present: I have walked two miles already [but I'm still walking]. I have run the Boston Marathon [but that was some time ago]. The critics have praised the film Saving Private Ryan since it came out [and they continue to do so].

1  . was the first prize won by John.
2. are our exercises  corrected each night by the teacher.
3. is The mail  delivered at ten o’clock.
4. will  the construction of the bridge be finished this year.
5. will the contract  be signed tomorrow.
6. What was listened to with great interest.
7. is the film  much spoken about.
8. Are all the letters looked through by the secretary.
9.were all these books  published by this publishing house.

1. The first prize wasn t  won by John.
2. Our exercises aren t corrected each night by the teacher.
3. The mail isn t  delivered at ten o’clock.
4. The construction of the bridge won t be finished this year.
5. The contract won t be signed tomorrow.
6. His report wasn t  listened to with great interest.
7. The film isn t much spoken about.
8. All the letters aren t looked through by the secretary.
9. All these books weren t published by this publishing house.