It has to be foolproof when he comes home.

他回家的时候，一定要绝对保险。

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Traveler's should always be aware: no security system is ever going to be foolproof and 100% secure.

旅行者们得时刻注意：没有任何的安全机制能被证明100%安全。

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The treatment will be tried out on human beings only after it has been shown to be safe and foolproof in animals.

该疗法只有在动物身上证明安全、万无一失后才会在人体上试用。

《柯林斯英汉双解大词典》

Apacs says that chip-and-pin remains the safest method of payment for goods and services but was never claimed to be foolproof.

BBC: Device 'steals chip-and-pin data'

But the Home Office also says none of these reforms has been shown to be foolproof in other countries - and in some cases have made the situation worse.

BBC: Prostitution: Local councils are pushing for reforms

Moreover, they are unlikely to be foolproof.

ECONOMIST: The shoulder-held threat | The