1、be confident in sb/doing sth 对某人充满信心/做某事
2、be confident about dong sth/sth 对某事/某事充满信心
例句：
1、You must be confident in what you do.
你必须对所做的事有信心。
2、Carrick also appears to be confident in his ability.
卡里克也对他的能力很有信心。
3、In the long term, Americans can have reason to be confident in our economic strength.
长期地看，美国人应该有理由对我们的经济实力充满信心。
4、"We still have to be confident about next season," he added.
“我们对下赛季充满信心，”他说。
5、It is too soon to be confident about its hypotheses.
现在还不能确信其假设的真实性。
扩展资料
对比：
But people should be confident in whatever road they choose.
但是人们无论选择哪条路都要有信心。
But by relying on these principles, we can be confident in the future of our Nation and the world.
但是依据这些原则，我们对我们的国家和这个世界的未来依然有信心。
Only with this exercise would I be confident in diagnosing a WHO grade II diffuse infiltrating astrocytoma.
只有这样认真校对之后，才能考虑本例是否为WHO分类的弥漫性浸润性星形细胞瘤II级
Do you know that it is also possible to be confident about life?
那么面对生命你是否也有同样的自信呢？
Be confident about yourself and your clothes.
对自己及所穿的服装要有信心。
参考资料：百度百科：英语语法
后面都可接doing sth，区别如下：
1、be confident in： 后面接某人，表示对某人充满信心
2、be confident about ： 后面接某事，表示对某事充满信心
例句
You must be confident in what you do.
你必须对所做的事有信心。
Carrick also appears to be confident in his ability.
卡里克也对他的能力很有信心。
It is too soon to be confident about its hypotheses.
现在还不能确信其假设的真实性。
扩展资料
Be confident about yourself and your clothes.
对自己及所穿的服装要有信心。
They don't seem to be very confident about the future of the industry.
他们似乎对该产业的未来信心不足。
You should be happy and confident about working with other people.
你应该对于和别人一起工作感到快乐、自信。
One has to be confident in himself.
一个人一定要对自己有信心。
But people should be confident in whatever road they choose.
但是人们无论选择哪条路都要有信心。
参考资料来源：百度百科：英语语法
本回答被网友采纳区别在用法上。
be confident in sb/doing sth，后面可以加人。
be confident about dong sth/sth，后面不可以加人。
例句：
be confident in
1、I am confident in him.
我对他有信心。
2、Confident in its camouflage, being the same colour as the rocks, the lizard stands still when it feels danger.
由于和岩石颜色一样，蜥蜴对自己的保护色充满信心；遇到危险时，它便一动不动。
3、Proficient and confident in performance.
精通的和表演自信的。
4、And I was confident in our relationship.
我对我们的关系很有信心。
be confident about
1、Management is confident about the way business is progressing.
管理层对业务发展的态势充满信心。
2、I was starting to feel more confident about the exam.
我开始对考试更加有信心了。
3、You should be happy and confident about working with other people.
你应该对于和别人一起工作感到快乐、自信。
4、I am confident about the future of China, he says.
我对中国的未来非常有信心，他表示。本回答被网友采纳