airlines and alliances, management homework help

according to strategic management book, a strategic alliance is a partnership btween firms whereby their resources and capabilities are combined to create a competitive advantge. so what is for an airline compay such as Unite. American or one of the three main alliances (one world, star or skyteam) 

Questions:

1. In general, why do airlines form an alliance with one another (particularly internationally) rather than expanding by acquisition?
2. What is the history of the alliance to which you were assigned?
3. Describe the main benefits that airlines hope to gain through membership. What is the competitive advantage of your particular alliance (if you find there is one)?
4. Categorise the alliance in terms of the three types of strategic alliance. Also describe the cooperative strategy of a member firm in relation to its business-level and corporate level strategy.
5. Think through issues of the future of airline alliances. If you were the CEO of a major US airline, what might worry you about your particular alliance, if anything?