Directions : Gap fillinginternal ; barrier ; abundant ; ruined ; obstacle ; destroy；external1. In other words, with hard work any ______ can be overcome.2. Lack of confidence is the biggest ______ to investment in the region.3. Humans as the creator began to ______.4. Once the wild were on the verge of extinction, the natural ecology be ______.5. They assist architects to communicate with _______ and _________design teams.6. Although the material resources are short, people has ________ spiritual resources.