重击确认没有必然成功，莫非这个还有疑问不成……
Automatic Misses and Hits: A natural 1 (the d20 comes up 1) on the attack roll is always a miss. A natural 20 (the d20 comes up 20) is always a hit.
Critical Hits: When you make an attack roll and get a natural 20 (the d20 shows 20), you hit regardless of your target’s Armor Class, and you have scored a threat. The hit might be a critical hit (or “crit”).
首先，当你做攻击检定的时候，20有两个作用，一，自动hit，无论对方AC多高；二，制造重击威胁。
To find out if it’s a critical hit, you immediately make a critical roll—another attack roll with all the same modifiers as the attack roll you just made. If the critical roll also results in a hit against the target’s AC, your original hit is a critical hit. (The critical roll just needs to hit to give you a crit. It doesn’t need to come up 20 again.)
其次，重击确认，依然是一个攻击检定（a critical roll—another attack roll ）。
重击确认只需要一个Hit，如前文，A natural 20 (the d20 comes up 20) is always a hit，20提供了自动命中（这里只是说自动命中，而和武器威胁范围无关。一个巨剑19-20，要自动命中依然要20……）如果出了20，那么自动命中，当然符合重击确认的要求……
Increased Threat Range: Sometimes your threat range is greater than 20. That is, you can score a threat on a lower number. In such cases, a roll of lower than 20 is not an automatic hit. Any attack roll that doesn’t result in a hit is not a threat.
这个也从侧面说，20是自动命中，而扩大了重击范围的武器，并没有扩大自动命中的范围。用巨剑投出了19，如果总合低于对方AC，由于无法命中，所以不但没办法产生重击威胁，甚至于不能制造伤害。但如果出20，由于A natural 20 (the d20 comes up 20) is always a hit这一原则，AC被无视，那么重击确认的时候，如果出20（而非19之类），那么自然是Hit……
嗯，这是我的想法，如果错了还请指正。
