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