一个数加7，再乘以3，然后减去12，再除以6，最后得到8，则这个数是______．
设这个数为x，
那么[（x+7）×3-12]÷6=8，
解得x=13．
Stressful environments lead to some unhealthy behavior such as a poor eating habit, which _____ increases
the risk of heart disease. [ ]
A. in turn
B. in return
C. by chance
D. by turns
所有居民均可免费享受健康体检中的辅助检查项目。
