有些HIV感染者并不清楚自己的感染状态，是传染源控制难点之一。
参考答案：对
I can't leave. She told me that I ____ stay here until she comes back. [ ]
A. may
B. must
C. can
D. will
数0.01010有效数字位数是（）位。
A、3
B、4
C、5
D、6
