神农二厂使用的石膏的含量指标是多少？
参考答案：含量不小于75.0%。
─Where can I find Jack?
─He _____ the post office. [ ]
A. has been to
B. had been to
C. has gone to
D. had gone to
根据中国九分法，双上臂、双前臂、和双手的面积分别占成人体表面积的（）、（）和（）。
