Up in the air
短语 up in the air 的意思是由于很多不定因素从而无法对某事的最终结果下论断，就像汉语里常说的“悬而未决“。
1. The doctor told me I can't travel because I need to get some vaccinations done first. I'm not sure I’ll be able to go on Wednesday - it's all up in the air!
2. It's all up in the air right now: no one can agree on whether to sell the company or not.
请注意:另一个和单词 air 有关的短语是 clear the air，它的意思是通过对话消除误会、隔阂。
1. My dad was really annoyed at me for forgetting his birthday. Last night we discussed it and cleared the air.
2. I didn't know how my wife felt about the situation, so last night we talked for two hours and cleared the air.
Nowadays, hot air balloon rides are popular with people looking for something fun and unusual to do. Ballooning is also one of the oldest means of manned flight transportation. In fact, the earliest flight by balloon can be traced back to late 18th century France. But, it’s widely recognised that China invented the first unmanned hot air balloons, the famous Kong Ming lanterns, originally used for military purposes.