No fence against flail.是什么意思？

No fence against flail.

飞来横祸不胜防.

no

adv. 不，否，一点也没有；adj. 没有的，不许的，一点儿也没有，决不是的；n. 不，否定，否认，反对票，否决票；abbr. 数字(number)，元素锘(nobelium)的符号；

例句
...a crime wave that shows no sign of abating.
丝毫没有减弱迹象的犯罪势头

fence

n. 栅栏，篱笆，围墙，防护物，剑术；vt. 用篱笆围住，防护，练习剑术；vi. 练习击剑，搪塞，围以栅栏，跳过栅栏；

例句
...a barbed-wire fence patrolled by armed guards...
有武装警卫巡逻的带刺铁丝网围栏

against

prep. 反对，对…不利，紧靠，以防；

例句
His hand brushed against hers; it could have been either accidental or deliberate.
就在有意无意间，他的手轻轻拂过她的手。

flail

vt. 用连枷打，鞭打，抽打；vi. 用连枷打，鞭打；n. 连枷（脱粒用的工具），扫雷装置；

例句
Knight assigned to guard Heigm Castle . Wields a Flame Flail . Was killed by and his battalion.
守卫王都海姆正门的骑士,持有火焰链枷. 死于德尼姆军的攻击下.