Never attempt to machine a work-piece without first checking the operation of the machine.( )
举一反三
- The ratio of the work done by the machine _________ the work done on it is called the efficiency of the machine.
- The ratio of the work done by the machine ______ the work done on it is called efficiency of the machine. A: against B: to C: with D: for
- The used old small typewriter is really （）. A: a piece of cake B: a piece of work C: a piece of junk D: a valuable machine
- The ratio of the work ______ by the machine to the work _____ on it is called the efficiency of the machine. A: to do ...to do B: doing....doing C: having done ... having done D: done ...done
- The machine is ___________ . A: in operate B: in operation C: in common