在mac上刚装完eclipse后，经常使用的eclipse辅助输入的快捷键竟然没有建议，纠结n久，最终还是在stackoverflow找到问题
Try restoring the default options in 'Windows > Preferences > Java > Editor > Content Assist > Advanced'
(example of the kind of data you see in this preference screen, not necessarily what you have though)
http://stackoverflow.com/questions/908489/eclipse-java-code-completion-not-working