关于友谊的英语句子有很多，以下是一些经典的和常用的表达：

Friendship is always a sweet responsibility, never a chance.

Friendship increases pleasure and reduces pain.

A gentleman and a gentleman are friends by their fellows, and a villain and a villain are friends by the same profit.

Wealth is not a friend, but a friend is a treasure.

The closer you are to someone, the more you affect them.

Promises are good for friendship, but it is good to cultivate and keep friendship through actions.

A true friend speaks the truth, even if the truth is harsh.

A true friend is a treasure for life.

Friendship is a sheltering tree, its roots deep, its branches strong, offering a cool respite in life's storms.

An old friend is a rare gem, precious beyond measure, shining bright in our journey's darkest corners.

True friendship transcends the boundaries of age, for it speaks the same language of shared experiences and understanding.

Thank you for hanging on my youth.

Taking friendship from life is like removing sunshine from life.

少年乐相知，衰暮思故友.

A friend in need is a friend indeed.

There is no friend so faithful as a good book.

Friends are like wine； the older, the better.

The best mirror is an old friend.

He who mistrusts most should be trusted least.

A true friend is one who gives you strength in your hour of need.

Friendship is a love without wings, but capable of flying.

Friendship is the only cement that will ever hold the world together.

If you would be loved, love and be lovable.

In prosperity our friends know us； in adversity we know our friends.

The only way to have a friend is to be one.

Friendship is not a trade, it cannot be bought or sold.

A friend is one that knows you as you are, understands where you have been, accepts who you have become, and still, loves you.

In the intensity of battles, friendships shine brighter.

Although time and distance separate us, we still remember the purest friendship and blessing.

这些句子涵盖了友谊的不同方面，包括它的价值、忠诚、陪伴、理解和支持等。希望这些句子能帮助你更好地表达和欣赏友谊的美好。