Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 26 to 30.

Ever since it was first possible to make a real robot, people have been hoping for the invention of a machine that would do all the necessary jobs around the house. If boring and repetitive factory work could be (26) ______ by robots, why not boring and repetitive household chores too?

For a long time, the only people who really gave the problem their attention were amateur inventors. And they came up against a major difficulty. That is, housework is (27) ______ very complex. It has never been one job, it has always been many. A factory robot carries out one task endlessly until it is reprogrammed to do something else. It doesn't run the whole factory. A housework robot, on the other hand, has to do (28) ______ different types of cleaning and carrying jobs and also has to cope with all the different shapes and positions of rooms, furniture, ornaments, cats and dogs.

(29) ______ , there have been some developments recently. Sensors are available to help the robot locate objects and avoid obstacles. We have the technology to produce the hardware. All that is missing is the software - the programs (30) ______ will operate the machine.