They are easy to break, most of them can be used only once.

它们很容易损坏，大多数只能使用一次。

youdao

The Caesar cipher is easy to break.

凯撒密码很容易破解。

youdao

Myth: SAML is easy to break using replay techniques.

不实说法：使用重播技术可以轻易地攻破SAML。

youdao

Lee soon discovered that it would not be easy to break out of the trap that Richmond and Petersburg had become.

VOA: special.2009.12.17

It is so hard to build trust between enemies and so easy to break it.

CNN: Diaries of hope and hate: Five days in the Middle East

But again, poor passing was letting them down as Watford found it far too easy to break down their forays forward.

BBC: Preston 1-1 Watford

But as recent events with CNOOC's bid for Unocal and Haier's bid for appliance giant Maytag have shown, it's not always easy to break into the Western market.

NPR: Chinese Telecom Companies Look to Global Markets