The group of students went to the suburb, did some research work, and ________ the water in the river to see if it had been polluted.
A. proved B. boiled C. tested D. exchanged
The group of students went to the suburb, did some research work, and ________ the water in the river to see if it had been polluted.
A. proved B. boiled C. tested D. exchanged
C
解析：test表示“测试；测验”，以确认是否合格。prove意为“证明”；boil意为“煮沸”；exchange意为“交流；交换”。