全血保存期的标准是根据输注24小时体内红细胞存活率为()
A．40％
B．50％
C．60％
D．70％
E．90％
参考答案：D
胡椒粒
对划线部分提问。
1. Marry and May are going hiking with their parents tomorrow.
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2. They are going to Qinghai for the coming field trip by train.
3. We are staying in London for two months.
4. We are meeting at the school gate at 2:00.
5. I'm going camping with my class next Sunday.
