useless单词相关例句：

No man is useless in this world who lightens the burden of someone else. ( C. Dickens )——    在这个世界上能为别人减轻负担的人都是有用的。（狄更斯）

expend sth. 付出 ⋯⋯ ，后面常跟名词 effort ， energy ， time ，strength 等。
expend sth. on sth. ; expend sth.in doing sth. 用在，花在 ⋯⋯
例句： Don't expend all your energy on such a useless job .
不要把你的精力全花在这无益的工作上。
同样表示花费、消耗的同义词有： cost 、 spend 、 take ，它们的区别是：
cost 指花费时间，金钱和气力，主语只能是物，且无被动语态。
spend 指花费时间，金钱，主语只能是人，有被动语态。
take 指花费时间，气力，主语一般是物。
例句： You don't need to expend that much time in watching TV .
你没必要花那么多时间在看电视上。

Our car was useless for want of petrol.

由于缺少汽油，我们的汽车派不上用场。

They are useless to us.

它们对我们没用。

It is useless for me to say whether my philosophy is valid or not for the Westerner.

我不必说我的哲学在西洋人的眼中是否正确。

It can abnegate useless samples and make the knowledge of study objects accumulate.

该算法舍弃对最终结论无用的样本，使得学习对象的知识得到了积累。

It will be useless learning a theory without practice.
A grammar rule, however true (it is), is useless unless it can be understood. 一条语法规则，不管如何正确，除非能懂，否则毫无用处。
A grammar rule, however true (it is), is useless unless it can be understood. 一条语法规则，不管如何正确，除非能懂，否则毫无用处。
A grammar rule, however true (it is), is useless unless it can be understood. 一条语法规则，不管如何正确，除非能懂，否则毫无用处。
useful单词相关例句：


We have all kinds of useful tools.
我们有各种各样的实用工具。


A Swiss Army knife contains many different useful tools.
一把瑞士军刀上有许多不同有用的工具。


Glue is very useful for sticking things together!
要把东西粘在一起，胶水会十分有用。


I'm too busy to get anything useful done.
我忙得都没时间做正事了！


This useful gadget allows you to draw a semicircle as well as a straight line.
这个有用的小工具能让你画半圆和直线。

The camel is a useful animal.

骆驼是一种有用的动物。

It's a most useful invention.

这是一项极其有用的发明。

It's a useful book for students.

这本书对学生很有用。

To provide a useful and consistent means of classifying attacks.

提供攻击一个一致且有帮助的分类方式。

N-COUNT. 副产品;派生产品. A spin-off is an unexpected but useful or valuable result of an activity that was designed to achieve something else.