If I see you through the glass, the object is going on some trajectory, which has got both up and down and horizontal motion.

如果我透过窗户看你，物体在一些轨道上，有上升和下降，也有水平运动。

youdao

The hyperbolic surface, which has so-called negative curvature because its surface curves up and down at the same time, like a saddle.

双曲曲面，即通常所称的负曲率，因为它的表面同时向上和向下弯曲，就像一个马鞍。

youdao

The network has shrunk by roughly a third since its postwar heyday, but more trains now trundle up and down the country than ever before.

自战后全盛时期以来，铁路网络已经缩减了约三分之一，但现在全国上下行驶的列车比以往任何时候都多。

youdao

"Now that the economy has gone down and the tuition's gone up - the army,they can pay for my college, so might as well do it."

VOA: standard.2010.07.14

The moon god has to come up at night and hang around for a while And go back down.

月神每晚都得出来，并且在天空悬一会儿,然后才能回去。

耶鲁公开课 - 旧约导论课程节选

That water is separated, that bubble has opened up so we've got the sky created And we've got the waters collected in certain areas down here, And we've got sky.

水流被分开，形成了水泡,我们便有了天空,在那里某些地方也有一些水流汇集，我们便有了天空。

耶鲁公开课 - 旧约导论课程节选

In May the Intel chief executive promised investors that sales and earnings will grow by double-digit percentages annually for years to come, even though the chipmaker's annual revenue growth has been just 2% over the past decade and net income has been very up and down.

FORBES: Magazine Article

His job has been up and down and he cannot afford to move out.

BBC: Why legal aid was the only option when I divorced

So has the up and down economy of the last few years affected her business?

FORBES: Meet Mary Louise Starkey, the Woman Behind "Butler Bootcamp"