概算定额的土石方体积是按自然密实方考虑的，某工程为缺方，需外购土，购土方量应按虚方计算。
参考答案：对
I’ve _____ my things at home.
A．forget
B．forgotten
C．left
D．lost
Unluckily, we missed the train. we early.
A．must have set out
B．had set out
C．should have set out
D．set out
