The red, formidable difficulties of war had been vanquished.

In fact, the purely formal question, which has occupied us in this last section, offers no very formidable difficulties.

Not surprisingly, this approach met with formidable operational difficulties.

There are formidable difficulties in trying to elucidate the situation.

But this presented, especially at that time, formidable difficulties.

Perseverance, patience, tact, and charity will help you conquer the most formidable difficulties.

I've read a lot about these games, and their formidable difficulty.

The young man's appearance, like the woman's suggested both the weariness of long travel and a remaining capacity to deal with formidable difficulties.

It is a book-length work, widely considered to present formidable difficulties to the reader.

However, the interdependence of hardware and software poses formidable technical difficulties to running programs so transferred.