空气中灰尘的存在可能引发过敏。

The ___presence of dust in the air can trigger allergies.

这份协议是在一位律师在场的情况下签署的。

The agreement was made ___in ___the ___presence ___of a lawyer.

学生们对特邀演讲者来到他们课堂表示欢迎。

The students welcomed the ___presence of a guest speaker in their class.