XI.

1. Bad weather made it impossible for the plane to touch down.

2.My brother is very fond of science fiction books.

3. Peter said that he had already seen the New-tech exhibition

4. They announced that the plane would be leaving in thirty-five minutes.

5. All household chores will easily be handled by a robot.

6.Thomas Edisonset up his first laboratory facility in 1876.

7.Mark suggested that we should go to the Science and Technology Fair.

8.It's not worth persuading him to go with us.

9.Why has noone come up with a way to make aircraft quieter?

10.By the time we arrived at the cinema, the film had finished. 

1. soundless

2. harmful_ harmless

3.hopeful_hopeless

4.thoughtful_thoughtless

5.helpful_helpless

6. colourful_ colourless

7.waterless

8.forgetful

9.careful_careless

11.wonderful

12.weightless

13. speechless

14.powerless_powerful

15.breathless

16.peaceful

17.homeless

18. beautiful

19.successful_successless

XI.

1. Bad weather made it impossible for the plane to touch down.

2.My brother is very fond of science fiction books.

3. Peter said that he had already seen the New-tech exhibition

4. They announced that the plane would be leaving in thirty-five minutes.

5. All household chores will easily be handled by a robot.

6.Thomas Edisonset up his first laboratory facility in 1876.

7.Mark suggested that we should go to the Science and Technology Fair.

8.It's not worth persuading him to go with us.

9.Why has noone come up with a way to make aircraft quieter?

10.By the time we arrived at the cinema, the film had finished. 

1. soundless

2. harmful_ harmless

3.hopeful_hopeless

4.thoughtful_thoughtless

5.helpful_helpless

6. colourful_ colourless

7.waterless

8.forgetful

9.careful_careless

11.wonderful

12.weightless

13. speechless

14.powerless_powerful

15.breathless

16.peaceful

17.homeless

18. beautiful

19.successful_successless