最下一只闸板防喷器内必须装有()闸板,此闸板应该能关住管串中任何规格的()。
参考答案:变径;钻杆或油管
九龙江是厦门的母亲河。下面四种说法中,代表一个生态系统的是
A.整条九龙江
B.九龙江的水
C.九龙江里所有的鱼
D.九龙江里的所有生物
___________a terrible storm would take place in Hainan [ ]
A Word came which
B. Word came that
C. Word that came
D. Words came that