But the most serious hurdle is the fact of a creation in which animals kill each other.

The most serious hurdle on his way to stardom was Argov's socioeconomic background.

Delayed or jittery signals are serious hurdles that developers of these applications must address.

Each of those companies, however, could face serious regulatory or legal hurdles.

The plan faces serious political hurdles in California, as well.

Even with Democrats back in power, organized labor faces serious hurdles.

Such projects will have to overcome serious hurdles.

But WorldCom never had a mobile phone business and so the cellular component of the deal is not likely to face any serious hurdles.

"We have some serious hurdles to get over."

Another more serious hurdle was the sound.