1. 表示“信赖，依赖，依靠”时，depend on/upon和rely on/upon常可换用。结构为：
depend on/rely on sb./sth.
depend on/rely on sb. to do sth.
We can depend on/rely on her words. 我们可以相信她的话。
Can you depend on her version of what happened?
你能相信她对所发生事情的描述吗？
They may hate what he does but their survival depends on him.
他们或许讨厌他的营生，但他们要想活下来必须依靠他
The community depends on the shipping industry for its survival.
这个地区靠航运业维持生活。
Our future prosperity depends on economic growth.
我们未来的繁荣昌盛依赖经济的发展。
Good education often depends on wealth.
良好的教育经常依靠良好的经济条件。
The peasants depend on a good harvest for their very existence.
农民靠丰收才能活命。
Communities on the island depended on whaling for their livelihood.
岛上的居民靠捕鲸为生。
All life depends ultimately on oxygen.
一切生命归根到底都要依赖氧气。
He depends on/relies on you to help him. 他依靠你帮助他。
How could you depend on his promise？你怎么能相信他的许诺呢？
The girl no longer depends upon her parents. 这小女孩已经不依靠父母了。
You counted on the stability of housing prices and depended on bankers to be, well, dependable.
曾经，你指望房价能稳定，这得依靠银行家，好吧，如果他们是可靠的话。
提示
rely on 语气比depend on重，多以人作主语。（尤与can/cannot/could/could not和should/should not连用以给予建议或承诺）指信任、信赖：
A man should rely upon his own powers in the struggle of life. 一个人在生活的斗争中应当依靠自身的力量。
Can I rely on you to keep this secret?
我能相信你会保守这个秘密吗？
You can't rely on any figures you get from them.
你不能相信从他们那儿得到的任何数据。
You can't really rely on his judgement.
你不能真的相信他的判断。
He can rely on my support when the crunch comes.
关键时刻，他可以依靠我的支持。
Can I rely on your support in the election?
我能指望你投我的票吗？
You can rely on him to respond to a challenge.
你可以信赖他，他懂得应付挑战。
2.depend on还可以表示“以……而定，由……而定，取决于”，这时不可用rely on。
It depends on yourself. 这取决于你自己。
Good health depends on good food, exercise and getting enough sleep.
身体的健康要靠良好的食物、锻炼和充足的睡眠。
It would depend on the circumstances.
这要视情况而定。
The success or failure of the plan depends on you.
这项计划的成败取决于你。
Whether we need more food depends on how many people turn up.
我们是否需要更多的食物，这要视到场人数而定。
The content of the course depends on what the students would like to study.
课程的内容取决于学生愿意学什么。
Does the quality of teaching depend on class size?
教学质量取决于每个班的人数吗？
Political power depends upon economic strength.
政治权力取决于经济实力。
Size of pension depends partly on length of service with the company.
退休金的多少部分取决于为公司服务时间的长短。
Our fees depend on the value of the trust.
我们的费用视信托金额而定。
Wage rates depend on levels of productivity.
工资水平取决于生产量的多寡。
It depends on the darkness of your skin.
这取决于你肤色的深浅。
The value of antiques will depend on their condition and rarity.
古董的价值依它们的保存状况和稀有程度而定。
He either resigned or was sacked, depending on who you talk to.
他或是辞职了，或是被辞退了，这要看你跟谁讲了。
It all depends on the weather clearing up.
这完全取决于天气是否会放晴。
3.depend用于It all depends或That depends结构中，意为“很难说，得看情况”，这时不可用rely。
Can you finish the work before Sunday？
It all depends.
你能在星期天前完成这项工作吗？这要看情况。
I don't know whether we'll have a picnic. It depends on the weather. 我不知道我们是否去野餐。那得看天气。