A
took, wanted, went, got, asked, thought, answered, could, was, remembered, said, opened
B
were driving
C
have lost, have found
1. I never ask him any questions.
2. Look! The teacher is drawing a picture on the blackboard.
3. When did you buy the cassette?
4. It's the best story I have ever read.
5. I have never seen so funny monkeys.
6. He enjoys playing the guitar.
7. I wrote the exercises an hour ago.
8. Who is using the telephone?
9. The sandwich is on the table, isn't it?
10. Jack has been to Rostov, hasn't he?
The term “internal combustion piston engine” referS to engines in which air and gasoline are buRNT inside the metal cylinders and which drive rotating crankshaft by means of piston and connecting rods. Since a great deal of heat IS produced when the gasoline mixture burns or explodes, some means must be provided to CARRY away the excessive heat. According to the cooling system employed the piston engines may BE CLASSIFIED as air-cooled engines and liquid-cooled ones.