斜拉桥拉索安装施工中,拉索抗振的约束环和减振器未安装前,必须确保索管(特别是梁上索管)和锚端的()、防腐和防污染。
A、防尘
B、防锈
C、防水
参考答案:C
DNA Shuffling
—Forests are very important to us,aren't they?
—Yes, they can prevent ________ from washing the earth away.[ ]
A. water
B. trees
C. grass