Which of the following is wrong about professionals and amateurs
A. No clear-cut distinction can be drawn between professionals and amateurs in science.
B. Amateurs' participation into scientific research has become more difficult.
C. There is no discriminations of professionals against amateurs in geology.
D. Entrance to professional geological journals has become harder for amateurs.
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根据井筒布置方法不同,矿井通风方式有()通风。
A. 机械式和自然
B. 压入式和抽出式
C. 离心式和轴流式
D. 中央并列式和中央边界式
按注浆工作与开挖、掘砌的施工关系,地层注浆方法分为()。
A. 水泥注浆、化学注浆
B. 充填注浆、劈裂注浆
C. 预注浆、后注浆
D. 帷幕注浆、堵水注浆
建筑用碳素结构钢牌号Q×××(如Q235)表示钢材的()。
A. 极限强度
B. 屈服强度
C. 剪切强度
D. 化学成分
Sound changes may include the loss of a sound or sounds. The so-called apocope refers to the omission of a vowel segment________. ( )
A. in word-initial
B. in word-middle
C. in word-final
D. in syllable-initial