化脓性膝关节炎的早期诊断中最有价值的方法()
A．关节肿胀及压痛
B．浮髌试验(+)
C．X线检查
D．关节穿刺液检查
E．血常规
参考答案：D
I know one of the things _____I was unsure about was _____ hard it would be to climb this mountain.
A．that; how
B．what; how
C．which; what
D．/; what
在原子吸收测定中，基态原子数不能代表待测元素的总原子数。( )
