It's up in the air 尚未确定

Up in the air 是习惯说法，指计划、问题等悬而未决、尚未确定。

The date of the wedding is still up in the air.婚礼的日期尚未确定。

When are you going to Australia? 你什么时候去澳洲？

It's up in the air.尚未确定。

Have you bought the new house? 你买了新房吗？

No, we have many choices but we can't decide which is best. So, it's up in the air.还没呢，我们有太多的选择，以致无法肯定哪一套最合适，所以还没有定下来。

When will you start to learn English? 你什么时候开始学英语？

Now I'm as busy as a bee. So it's up in the air.现在我特别忙，所以无法确定。

Pick up the pace 加快脚步

pace 的意思是步态、步伐、速度。Pick up the pace, 意思是加快脚步、加快速度。在英语中，表示催促的词组，除了pick up the pace. 还有Hurry up! Come on! 等。

We're late for the banquet. Pick up your pace! 我们赴宴迟了，快走吧！

You go first. I'll follow after I change my clothes.你先走，换好衣服后我会跟上你。

Happy Valley Theme Park is going to close. Could you pick up your pace so we can try to see the whole park? 欢乐谷就要关门了，快走吧，我们争取到每个地方去看看。

OK, I agree.好吧。

The sports lesson will start soon. Pick up your pace, your sports teacher is hot-tempered.体育课就要开始了，快点吧，你们的体育教师可是个爆脾气。

The enemy is coming soon. Pick up your pace! 敌人就要到了，加快脚步前进！

Pick up your pace. It will start raining soon.快点走，开要下雨了。