它使用一个安装在后面的推进式螺旋桨并有一对一上一下反向旋转的主旋翼。

The X2 uses a pusher propeller mounted at the rear and has a pair of contra-rotating main rotors, one positioned above the other.

youdao

他们一直过着一上一下的生活，就是为了这种信心；这是一种倚靠环境的信心。

They led an up and down life because of this kind of faith; it was a faith that depended upon circumstances.

youdao

你要做两个盆子，一上一下。两个盆子之间的空隙能让泥泵通到下面盆子的底部。

One would create two basins one on top of the other the space between the two basins would allow a dredge pump to access the bottom of the lower basin.

youdao

Let's begin with a kind of warm-up sheet which we can anchor in these little drawings I've made.

让我们先来热一下身,看一下我在黑板上画的图。

耶鲁公开课 - 文学理论导论课程节选

As we go across the row what happens is that the ionization energy actually increases, and we can think about logically why it is that that's happening.

当我们沿着行,向右走的时候，可以发现电离能是逐渐升高的,我们可以从逻辑上思考一下为什么会这样。

麻省理工公开课 - 化学原理课程节选

Now incidentally, often bank loans to corporations are short-term, technically, so the bank is both lending short and borrowing short.

顺便说一下,技术上讲,银行借给公司的都是短期贷款,银行同时进行短期借贷业务

耶鲁公开课 - 金融市场课程节选