一、用under表示

1. 表示具体意义的“在……下”。如：

Your bag is under the bed. 你的提包在床底下。

She put the letter under the pillow. 她把信放在枕头下。

Under a microscope a hair looks like a thick stick. 在显微镜下，一根头发看上去像根大粗棍子。

2. 表示抽象意义的“在……下”。如：

We did the work under his direction. 我们在他的指导下工作。

Under present conditions no change is possible. 在目前情况下不可能有变化。

It’s hard to stay sane under such awful pressure. 处于这种可怕的压力之下，不疯才怪呢。

The group flourished under her firm leadership. 这个团队在她的坚定领导下兴旺发达。

Under the new management things have gone from bad to worse. 在新的管理人员领导下，情况反而更坏了。

二、用in表示

The trees threw long shadows in the moonlight. 在月光下，树木投出了长长的影子。

Make sure that the figures on the dial can be seen in direct sunlight. 要确保刻度盘上的数字在日光下可以看见。

In given conditions a bad thing can be turned into a good one. 在一定条件下，坏事可以变为好事。

Time is an important consideration in this case. 在这种情况下，时间是一个要考虑的重要因素。

In the ordinary course of events, I visit her once a week. 在一般情况下，我每周去看她一次。

In most instances the pain soon goes away. 在多数情况下，这种疼痛很快就消失。

三、用with表示

He got back his wallet with the help of the police. 在警察的帮助下，他找回了自己的钱包。

With the teacher’s help, I worked out the problem at last. 在老师的帮助下，我终于算出了这道习题。

I left as early as was consistent with politeness. 我在不失礼的情况下，提前离去了。

四、用by表示

He worked by the light of a candle. 他在烛光下工作。

Animated by fresh hope, he started again. 他在新希望的激励之下，又从头做起。

五、用to表示

Don’t expose your skin to the sun for long. 别让皮肤长时间暴露在阳光下。

六、用through表示

He got his job through a friend. 在一位朋友的帮忙下他得到这份工作。

七、用beneath表示

The river flows beneath the old bridge. 小河从那古老的桥下流过。

The sun is now beneath the horizon. 太阳此刻落到地平线下了。

I had arranged to meet him beneath the statue in the park. 我和他约好在公园的塑像下碰头。

八、用其他方法表示

Quite unknown to me, she’d gone ahead and booked the holiday. 在我完全不了解的情况下，她已先行办好了度假的预订手续。

I was hurried into making an unwise decision. 我在催逼之下草率地做出了不智的决定。

Higher salaries are seducing many teachers into industry. 在高薪利诱之下，许多教师改行进入工业界。