管道胸腔回填土采用人工或蛙式打夯机时,每层厚度按()分层填筑。
A.15cm
B.20cm
C.25cm
D.30cm
参考答案:B
Don't worry. Jim is quite used to _____ in such busy streets as this.[ ]
A. drive
B. be driving
C. have driven
D. driving
第16~25小题,要求判断每题给出的条件(1)和(2)能否充分支持题干所陈述的结论.A、B、C、D、E五个选项为判断结果,请选择一项符合试题要求的判断.A.条件(1)充分,但条件(2)不充分. B.条件(2)充分,但条件(1)不充分. C.条件(1)和(2)单独都不充分,但条件(1)和条件(2)联合起来充分. D.条件(1)充分,条件(2)也充分. E.条件(1)和(2)单独都不充分,条件(1)和条件(2)联合起来也不充分.
方程|x+1|+|x|=2无根. (1) x∈(-∞,-1) (2) x∈(-1,0)