Sentence examples for were difficult to observe from inspiring English sources

A contingent of the international news media came to Kabul to cover the proceedings, which were difficult to observe.

Thus, since the majority of the GFP- tagged-Kb tumor cells weekly expressed GFP, it is possible that after DC uptake and display, the relatively small numbers of Kb molecules/peptide complexes that were transferred were difficult to observe with fluorescence microscopy techniques.

Spherulites were fine, with diameters of a few micrometers only, so details of the structure were difficult to observe.

However, these cells were difficult to observe and quantify since they are embedded within the (calcified) matrix (Fig.  3).

*S1, aviary section in which cumulative mortality rate could not be estimated because exact bird population was not known and birds were difficult to observe; S2, aviary section in which captive bird population was exactly known and number of dead birds was precisely recorded; NP, species not present in S1 or S2.

For S1, the cumulative mortality rate could not be estimated because the exact bird population was not known and the birds were difficult to observe in that section (the semicaptive waterfowl population is able to mix with the wild population and disperse to breed).

These prohibitions are difficult to observe.

Like many other geologic features concealed beneath the earth, caves are difficult to observe.

This female finally got into a posture that enabled copulation, a process that is as strange in spiders as it is difficult to observe.

Because the Hawking emissions would be obscured by more powerful radiation sources in space, it would be difficult to observe with astronomical instruments.

Chain said the model provided strong evidence of cell-to-cell spread, which he said some HIV scientists remained sceptical about, as it is difficult to observe in human beingsbecause it occurs in tissue.