Sentence examples for been difficult to observe from inspiring English sources

However, it has been difficult to observe the ovule consistently in a specific position because ovules are randomly dispersed on a substrate with conventional methods.

Yet with all of our current knowledge of tumor biology, the details of early oncogenesis have been difficult to observe and understand.

For instance, the distance traveled across the arms of the apparatus or the time spent on each arm would have been difficult to observe and record precisely.

From here on Earth, this region has been difficult to observe, obscured by clouds of dust and gas.

But this structure has been difficult to observe because the surface of Saturn is obscured by a thick haze that is difficult to penetrate.

To date, however, sponging, which occurs almost exclusively in deep water channels [11] has been difficult to observe, and consequently has not been described in detail.

These prohibitions are difficult to observe.

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