By 1960, you were twice the natural level. And '63-there was a test ban treaty, so '63 was the maximum.

到1960年，大气中的碳14含量为自然水平的两倍。但1963年出台了禁止试验条约，因此碳14含量在该年达到最大值。

The terrorists were forced to sign the test ban.

恐怖分子被迫签署了禁止核试验协定。

And this is ultimately why when a test ban treaty was signed in 1963, it was only a partial ban.

这就是为什么 1963 年签署禁止试验条约时，只是部分禁止。

But there was a big problem with negotiating a comprehensive test ban which is how do you know that the other side will hold up their end of the bargain?

但全面禁试谈判有一个大问题，那就是如何知道对方会履行诺言？

A number of world leaders called for a comprehensive test ban, no more testing of nuclear weapons by any state and this call was actually taken seriously by the world's nuclear powers.

多位世界领导人呼吁全面禁止核试验，任何国家不再进行核武器试验，这一呼吁实际上得到了世界核大国的重视。