甲烷传感器在新鲜空气中调仪器零点，零值范围控制在0.00-0.03%CH4之内。
参考答案：对
人体通过清除粉尘的各种功能，只有（）
A.不到0.1%的尘粒沉积在肺内
B.0.1%～0.3%的尘粒沉积在肺内
C.1%～3%的尘粒沉积在肺内
D.10^～30%的尘粒沉积在肺内
E.10%～50%的尘粒沉积在肺内
It was not until she got home ______ Jennifer realized she had lost her keys.
A．when
B．that
C．where
D．before
