1. Back in the early 1960s, when the laser was first being developed, it was viewed by some as a fascinating research tool, others called it a science-fiction toy.
    追溯到二十世纪六十年代初期,当激光最初被开发利用时，一些人视之为神奇的科研工具，另一些人则称之为科幻小说里的玩具。

2. A hammer is a tool for knocking nails into wood.
    锤子是用于把钉子打入木头的工具。

3. You can use a convenient tool.
    你可以用一个合适的工具。

4. Is cloning morally wrong and dangerous — or is it a valuable research tool?
    克隆是违背或危害道德的——还是一种有价值的研究手段？