| 1. | It is useful to think classically .
根据经典的观点来思考问题是有用的。 |
| 2. | It is useful to have a convenient supermarket .
附近有家超级市场实在方便。 |
| 3. | I am glad you think i have been useful to her .
你认为我帮了她的大忙，我很高兴。 |
| 4. | She found many different ways of being useful to him .
她在许多别的事情上为他效过劳。 |
| 5. | It is useful to partition a graph into its components .
把一个图分解成它的分支，是很有益的。 |
| 6. | It is useful to classify all these particles into two groups .
把所有粒子分成两大类是适当的。 |
| 7. | It will be useful to summarize the relevant gaussian formulae .
有必要概括地讲一下有关的高斯公式。 |
| 8. | Two alternative systems are useful to avoid this stalemate .
此时采用下列两种系统之一便可加以解决。 |
| 9. | If the wind were contrary, they might be useful to us .
假使碰到逆风的时候，它们还可以为我们服务哩。 |
| 10. | It is useful to have checks against arithmetical errors .
为防止算术计算中的错误，加以验算是有益的。 |
