无菌罐的大修周期是1500小时。
参考答案:对
--- _____ you_____your room yet?
--- Yes. I_________it a moment ago.
A.Did;clean;cleaned
B.Have;cleaned;have cleaned
C.Have; cleaned; cleaned
D.Will; clean; clean
机体中储存于骨骼的磷含量为()
A.20%
B.40%
C.60%
D.80%