当空气中的氧含量低于()%,简易防护面具不能使用。A.15 B.18 C.20 D. 发布时间:2017-11-15 04:36 │ 来源:www.tikuol.com 题型:单项选择题 问题: 当空气中的氧含量低于()%,简易防护面具不能使用。A.15B.18C.20D.21
题型:单项选择题 When the people in the area heard the news that a rare vase which was used by an emperorduring the Ming Dynasty was buried somewhere near their homes, they all went out ___ it. [ ]A. to search B. to look at C. in search for D. in search of 查看答案
题型:单项选择题 He was no longer _______ by the news of his mother’s death.A.affectedB.effectedC.effected onD.affected to 查看答案