就地灌注和爆扩桩应在桩身混凝土强度达到设计等级的前提下,对于()不应少于30d才能进行试验。
A.砂类土
B.粉土
C.黏性土
D.淤泥或淤泥质土
参考答案:D
The teacher asked Jim _______________.
A.why was he late for school
B.why he was late for school
C.how he was late for school
D.how was he late for school
二次系统上的工作人员在现场工作过程中,遇到异常情况(如直流系统接地等)或开关跳闸时,若是本身工作所引起,应( )并立即通知( ),以便及时处理。