单项选择题
A．Newborn babies can use both hands well B．Most human beings use their right hands better C．Few human beings use their left hands D．We live in a right-handed world
A．a stepladder used to have four legs. B．it is dangerous to use tools C．a tripod is safer in a tool design D．workers are safer on production lines
A．5 per cent of the world’s water B．15 percent of the world’s water C．20 percent of the world’s water D．50 percent of the world’s water