Original sentence: On the other hand, its been reported that Chinese has been used as the medium of instructions in some autonomous counties even though less than 50% of the population "spoke and understood some Chinese"; this mismatch was though to have contributed to the low grades earned by the students on the math and Chinese exams
Edited sentence: On the other hand, it has been reported that Chinese has been used as the medium of instructions in some autonomous counties even though less than 50% of the population "spoke and understood some Chinese"; this mismatch was though to have contributed to the low grades earned by the students on the math and Chinese exams