To a certain extent, we are all responsible for this tragic situation.certain extent

He had changed to such an extent (= so much) that I no longer recognized him.to such an extent(= so much)

To some extent what she argues is true.To some extent

The pollution of the forest has seriously affected plant life and, to a lesser extent, wildlife.to a lesser extent

To what extent is this true of all schools?To what extent

The book discusses the extent to which (= how much) family life has changed over the past 50 years.the extent to which(= how much)