山东省金矿的分布主要集中于东部地区,以威海为主。 ( )
参考答案:错
He is terrified of ___ alone in the street at night.[ ]
A. to walk
B. having walked
C. walking
D. walked
强制送风呼吸器使用环境中氧气浓度不得低于多少?()
A.0.15
B.0.2
C.0.19
D.0.1