the dodo bird once lived in the mascarene islands. since the dodo had no natural enemies on theme islands, the species 1.stopped developing ways to save itself. these strange binds 2.discovered by portuguese sailors who came to explore the islands in the early 1500s. they 3.tried hunting the birds and found that could kill them easily. the sailors 4.killed many dodos to eat. pigs and monkeys killed others. before long 5. there were none left

답은 2번 앞에 were 집어넣어야 한데요.. 왜요? 1번은 stop다음에 ing 알겠고요 3번도 try다음에 ing알겠는데 2,4,5번 2번은 왜 were 이 들어가야되는지 몰겠고 4,5번은 맞는데 왜 맞는 답인지 몰겠어요 ㅠ

one of the most important weapons [used /using]during the second world war was not a weapon used against people, but rather a drug used against disease. the wartime use of penicillin saved thousands of lives. in the first worlk war, for example, pneumonia was responsible for eighteen percent of all the deaths in the united sates army. in the second world war, the rate went down to less than one percent. in additions, penicillin was helpful in keeping wounds from [getting infected / infecting]and in helping to speed up the healing process of those wounds.

답들은 used, getting infected인데요 이유를 모르겟어요