It is a tiny effect that is difficult to confirm experimentally.

It is a small effect, difficult to confirm experimentally.

It is also a tiny effect that is difficult to confirm experimentally.

The second force will always be difficult to verify.

Therefore, an infestation may prove difficult to confirm.

Therefore, it can be difficult to confirm an infestation.

A fibromyalgia diagnosis can be difficult to confirm.

It is hard to know when the debate takes place behind closed doors.

It’s hard to know because the deliberations all take place behind closed doors.

It is difficult to say to say because the deliberations took place behind close doors.

We can only guess, since the discussions are held behind closed doors.

It is hard to test this without a complete implementation.

Their exact number is hard to confirm, as they keep a low profile.

However, the wide range of causes makes this difficult to confirm.

The extent of Küçük’s involvement in the Afrin operation is hard to confirm.