An ancient civilization might have carve the horse into the grass in the Bronze Age.

Human hands may have created them, because they are a near perfect sphere.

Environmental factors like water and wind couldn’t have formed the stones in this round shape.

An advanced civilisation must have drawned the inscriptions on the disk.

The inscriptions might have been a message to the gods.

She must have been cold, because she wasn’t wearing a jacket.

She must have fell happy when she arrived, because she was smiling.

She may had visited the temple to meet someone inside.

She might have ran out again because she had forgotten her bag.

If I had studied last night, I wouldn’t have failed my Math exam.

We wouldn’t have been to space if science and technology hadn’t developed.

If we hadn’t investigated the source, we wouldn’t have found out it was a hoax.

We would have seen photos, if a photographer had been there.

If aliens had visit Earth, we would have found evidence. 

If you had been here earlier, you would have saw the UFO.

We would have found debris by now if there had been a crash.

He wouldn’t have come if I hadn’t invited him.

If scientist had discover evidence of aliens, we would have heard about it.

If we had solve the mystery, what would the police have said?