Hundreds of "friendly" robots that speak multiple languages and sing are being rolled out across hi-tech Singapore, to help clean the city-state's hotels, shopping malls and government buildings.Four of the robots, which have oval-shaped heads with lights for eyes, have already got down to work and it is hoped that 300 will be put into service by March next year.They scrub, mop, vacuum and sweep autonomously, and can entertain by rapping in English.The robots speak all four of