连词的复杂用法

连词的复杂用法
最近在做关于连词的练习,找了道比较难的,可以有人帮我做出答案吗?
____people think of global travel,they think of expensive cruise ships or sightseeing tours to famous places.____global travel has changed a lot in recent years.Now not all travel is expensive_____lack of money does't have to hold people back.____these days there is an enormous variety of possibilities for people of all interests.
Approximately 20 percent of all international travel is now nature travel,or ecotourism.Serious ecotourists are interested in preserving the environment____learning about wildlife.____many want to learn about a new culture.____it's possible to be very comfortable on an ecotour many travelers choose to rough it____they don't expect hot showers,clean sheets,gourmet food,____air-conditioned buses.____they want to live as villagers do,they get around on bicycles,on foot,____on the water.
____people want a valuable experience abroad,they can study____volunteer-at the same time.____they go to the vijnana kala vedi cultural center in india,they can study two subjects,among them indian music,dance,theater,cooking,____yoga.the tuitiong for these classes____room and board is very low______the participants volunteer one hour each day to reach English to children in the village.____people are interested in science,______they can study specific science in a hands-on experience______they volunteer on aresearch project through the organization called EARTHWATCH.