Reflux, however, can sometimes be difficult to control and may jeopardize a complete embolization.
In an environment where "only results matter," it can sometimes be difficult to recognize the risks.
In appearance, autocracy may sometimes be difficult to distinguish from nonautocratic rule.
In the city that never sleeps, it can sometimes be difficult to decide what to do.
It may sometimes be difficult to ascertain whether a transfer of copyright is voluntary or is coerced by covert pressure.
"But especially at busy construction sites, it can sometimes be difficult to be aware of who's coming and going".
But it can sometimes be difficult to differentiate between a militant act, street art, vandalism and madness.
It may sometimes be difficult to enforce the law because of the international nature of the internet.
The people who run real estate investment trusts, or REITs, can sometimes be difficult to track down.
You often get access and credibility that may sometimes be difficult to get if you have only been in business".
However, the principal components (PCs) can sometimes be difficult to interpret, because they are linear combinations of all the original variables.
