In no other way could he account for this phenomenon.

We do not yet have an explanation for this phenomenon.

Scientists must be trying to discover the reason for the phenomenon.

I had simply found a practical application for the phenomenon.

The reasons for the phenomenon in this country are unclear.

However, there are a number of natural explanations for this phenomenon.

We must not get fishermen to foot the bill for natural phenomena.

One may well speculate on possible causes for the phenomenon.

It almost certainly never occurred to anyone before then that human attention might be a necessary condition for the phenomenon.

These weapons are also largely responsible for the phenomenon of child soldiers.