in.

常见例句

The wind was whispering in the trees.
一阵风穿过树林沙沙作响。
There are 26 letters in the English alphabet.
英语字母表中有26个字母。
There is a vein of melancholy in his character.
他的性格中有少许忧郁的气质。
There was a long lag in forwarding mail to us.
转寄给我们的邮件晚了很久才拿到。
A cloud is a mass of vapor in the sky.
云是天空中的水汽团。
A fire was burning in the grate.
火在壁炉中燃烧着。