石灰岩、砂岩、页岩都属于()。
A.岩浆岩
B.变质岩
C.砂砾岩
D.沉积岩
参考答案:D
---Why did he___ that the man we met on the bridge was his father?
---God knows!
A.refuse
B.deny
C.accuse
D.resist
叙述地面控制的安全阀的主要优点和缺点(与井下控制的安全阀相比)。