There was a time when a C meant average. The average GPA at four-year colleges and universities has risen from 2.52 in the 1950s to 3.11 in 2006. And according to Stuart Rojstaczer, a former Duke University professor and founder of GradeInflation.com, GPAs only keep rising. At some colleges, Rojstaczer says, over 50% of the grades given are A's.
Trench warfare was caused by an advance in defensive weaponry. The machine gun was too heavy to be used as a mobile weapon, and therefore was placed into a fixed position. Barbed and concertina wire was also heavily used.
This is a style of tactics used in WWI where Germans and French  armies used to dig trenches to shelter them from enemy fire, using  the trenches as positions from where to assail the other's  trenches. Trench warfare is often used as an opposite of movement  warfare. + 64 others found this useful.