сделать 1. The translucent properties of this ceramic (1)(first/discover) by NASA ceramic engineers.

2. They (2) (carry out) research to (3)(develop) tough new materials when they suddenly (4)(notice) that light (5)(pass) through one of the ceramics.

3. Now, however, the ceramic (6)(commonly utilise) by dental engineers for (7)(make) protective braces, or restraints, for children’s teeth.

1) a) were first discovered b) had been first discovered c) have been first discovered

2) a) carried out b) had carried out c) were carrying out

3) a) developing b) develop c) have developed

4) a) have noticed b) noticed c) were noticing

5) a) passed b) was passing c) had passed

6) a) commonly utilised b) was commonly utilised c) is commonly utilised

7) a) making b) being made c) make

1 I work. We work 2. 'They do not work 3. 4 Do you work? - - Yes. | 5. it work? - - No. He's learning. 6 My brother | is not learning. It works. 7 My sister does not read books. 8 Our grandmother likes to sleep on the couch. 9 You like to relax in a chair? 10 We eat and drink in the kitchen. 11 My brother likes to read the newspaper. 12 We sleep in the bedroom. 13 My brother is sleeping on the couch in the living room. 14 My sister dressed in front of a mirror. 15 My uncle wrote a book. 16 We are writing exercise in school. 17 When you get up? - - I get up at a quarter to sem.18. When it comes your brother? - - He stands at twenty-eight. - And your sister, too, stands at twenty-eight? - - No. My brother goes to school, and my sister did not go to school. It is not yet a pupil. She gets up at nine o'clock

1 I work
2 we work
3 They aren't work
4 Do you work? yes I do.
5 Does he work? No, he studies.
6 My brother doesn't study. He works.
7 My sister doesn't read books.
8 Our grandmother likes to sleep in sofa.
9 Do you like to have a rest on armchair. 
10 We eat and drink in the kitchen.
11 My brother doesn't like to read newspapers.
12 We sleep in bedroom.
13 My brother sleeps on the couch in the living room.
14 My sister gets dressed in the front of mirror.
15 My uncle writes books.
16 We write exercise ar school.