Sentence examples for proved difficult to grow from inspiring English sources

The vaccine is made with a live attenuated virus that has proved difficult to grow in bulk, and also is needed to make the childhood chickenpox vaccine, said Dr. Eddy Bresnitz, global medical affairs director of Merck Vaccines.

But diplomats say it has proved difficult to generate much sympathy for grown men who admitted to having worked for Cuban intelligence.

The toxic dinoflagellate Gambierdiscus has also proved difficult to maintain in culture; it grows slowly and does not attain high biomass [ 66- 68].

Although recent outbreaks of food-borne disease caused by E. coli and Salmonella have been well documented, and may, in part, be due to increased consumption of uncooked and organically grown vegetables, it has proved difficult to elucidate the full range of factors involved and therefore manage the risks to human health from pathogenic bacteria in the environment.

But, according to the article, he grew increasingly uncomfortable with his career choice as it proved difficult to keep his private and NHS work separate.

Genocide has proved difficult to prosecute.

The effect proved difficult to measure.

The latter aim proved difficult to enforce.

Yet reform proved difficult to implement.

The furlough plan proved difficult to enforce.

The advice proved difficult to follow.