1.At present,about 300 (different) varieties (of dinosaur) have been identified from (bones found) on (every) of the continents.
错误的是D,every.为什么?dinosaur不应该变成dinosaurs吗?
2.By 1996,the US population (exceeded) 261 million,with a median (age of) thirty-four,(making) it one of the oldest national (population) on earth.
错误的是D,exceeded 不用改成had exceeded吗?
3.Missouri is a (heavily) industrialized state (whose) (leading) products are transportation equipment,processed food,and (chemical).
为什么?