1 . In short, the tourism industry is facing t__________ (艰难的) challenges and it has to turn those challenges into opportunities. (根据中英文提示单词拼写)

2 . With nobody forcing her to do so, Mary helps to work as a v________ in a local hospital every week because she finds it meaningful. (根据首字母单词拼写)

3 . Best results can be _________ (获得) by starting the plants off in a warm greenhouse. (根据汉语意思单词拼写)