The strain appears to be a particularly vigorous one.

In recent months, officials say, a more fastidious strain of token sucker has also appeared.

When Torres came back last year, however, some strain appeared to develop between her and Thompson.

Suddenly, in the 1950's, the first penicillin-resistant strains of staph appeared.

As if a different strain could appear in a month's time.

For some working women, the strain of two jobs appears to have made an impression on the men with whom they live.

Certain strains appear to be helpful only for certain conditions.

The strains of mycoplasma in patients he has seen appear to resist treatment with antibiotics.

The human strains appear to have diverged from the simian 3600 years ago.