Cullen, a Scottsh professor, ____1_____ a small refrigeration machine in 1755, using a pump to ____2_____ a partial vacuum over
a ___3_____ of diethyl ether, _____4______ then boiled, absorbing heat from the surrounding air. At the time, it had no practical use and _____5_____ never found a use for his invention.
1. designed , designs , was designing , have designed
2. creation , creating , create , creative
3. containing , container , containers , contained
4. whom , when , who , which
5. them , Cullen , cullen , him
GRAMMAR HELP ME PLEASE ,,,
