SAT语法题2道
1.The Pacific Northewest (averaging 4000 wildfires a year,caused mostly) by lighting.
A.原句
B.averages 4000 wildfires a year; most are caused
D.with an average of 4000 wildfires a year,caused mostly
PS：括号内是A选项
问：为何原句和D选项是错的
2.An entire ant colony working together can solve problems,（such as when they find） the shortest path to a food source ,that are impossible for an individual ant to solve.
A.原句
B.such as finding of
C.such as finding
问：B选项为什么不对