1. A run-down watch is still a watch and can be rewound. An old watch, by contrast, becomes so worn and unreliable that it eventually is not worth mending.
    手表停了依然是只手表，还可以重上好发条。然而一只老掉牙的手表，磨损太厉害，老得一点儿不准了，最终不值得修理了。

2. In the early 1950s computers were expensive and unreliable.
    在二十世纪五十年代初期, 计算机价钱很贵, 而且也不可靠。