Weather conditions can changequickly, making preflight briefings obsolete.
天气状况变幻莫测，使得飞行前的天气信息失去时效。
2
They can't cover all possible weather conditions which tend to changequickly.
它们不能覆盖所有的天气情况，天气变化太快了。
3
Firstly, during the period of open loop control, system traces the change of LPG injection of engine quickly by checking the pre-set two-dimension MAP if conditions of engine are changed suddenly.