Sentence examples for historically been difficult from inspiring English sources

The depth of glaciers has historically been difficult and costly to study accurately.

Although cassava has historically been difficult to breed, HarvestPlus has developed vitamin A cassava through selective breeding.

Urothelial carcinoma of the bladder is a common malignancy which has historically been difficult to treat in its advanced stages.

"This will propel a step-change in knowledge and technology, which will facilitate exploration by private companies in areas that have historically been difficult to explore".

While the UK is a world leader in areas such as engineering design and aerospace, it's historically been difficult to get new ideas to market.

BUT the transition from wartime has historically been difficult for presidents -- though Dwight D. Eisenhower might have cashed the ultimate war dividend check with his election.

Here we describe the application of one such fragmentation method, combinatorial domain hunting (CDH), to a target which historically was difficult to express, human MEK-1.

The force of these has confused modern commentators for a combination of reasons which, historically, are difficult to untangle.

The degree to which the AZ profiles reflect the particular set of targets that they have investigated historically is difficult to assess but it probably has some influence.

The development of effective treatment for stimulant addiction historically has been difficult.

Considering overall SVR 12 rates, patients with HCV genotype 1 infection, which historically have been difficult to treat, still seem to be the population hardest to cure, as also reflected by our study results [ 10, 14, 17].