They will have to cancel the show if the number of the audience doesn't increase.

• This means that the show will be canceled unless the number of the audience increases.

They were amazed by the fact that their house was broken.

• To their amazement, their house was broken.

The earth is experiencing a reduction in global biodiversity.

• There is a reduction in global biodiversity on Earth.

In 1960 environmental concerns entered the main stream of the US political debate.

• It was not until 1960 that environmental concerns entered the main stream of the US political debate.

They accept that the movement was successful.

• They have accepted the success of the movement.