Some areas should be kept secure as a failsafe because mustard gas can be very persistent in the environment, he warned.

部分地区必须采用故障保险机制，因为芥子气在环境中可以长久的存留。

youdao

Thee persistent haze weather, around the introduction of a number of measures to improve air quality, such as vehicles, the elimination of old vehicles, replacing oil by gas and so on.

针对持续的雾霾天气，各地出台不少措施来改善空气质量，如限制车辆出行，淘汰老旧车辆，以气代油等等。

youdao

In effect, bond market investors are slamming down on the gas pedal while Banks, burdened by persistent regulatory demands, still have their foot on the brake.

实际上，尽管债市投资者在猛踩油门，但受困于严苛监管要求的银行，仍然在踩刹车。

youdao

Its authors said the extensive and persistent use of tear gas against civilians by Bahrain's security forces during the past 18 months was unprecedented in the 100-year history of its use throughout the world.

BBC: Bahrain authorities 'weaponising' tear gas

Since electricity supply was privatised in the 1990s, there have been persistent complaints that suppliers have employed salesmen who set out to trick customers on their doorsteps into switching from their existing gas or electricity firm.

BBC: MPs call for energy doorstep mis-selling compensation