1 . What made him excited was that he was offered ___________amazing opportunity to work with leading scientists in the field. (用适当的词填空)

4 . Travelling Amazon Rainforest is such ________ unusual experience that the following trips to other places in Peru are desirable. (用适当的词填空)

5 . These inventions have brought us happiness and are performing _________important function in our life. We shouldn’t ignore their disadvantages. (用适当的词填空)

7 . There are alternative _________(source) of nutrition to animal meat. He has shared one view and I have expressed ____ alternative way of seeing it. (所给词的适当形式填空)