标志图形的符号为黑色,底色为白色的危险货物是()。
A.一级放射性物品
B.二级放射性物品
C.毒性物质
D.感染性物质
参考答案:A, C, D
—How was your trip to Yancheng last week?
—Wonderful! I only felt sorry that I ________ the nature reserve of redcrowned cranes, but the weather was awful.
A.could visit
B.could have visited
C.might visit
D.might have visited
剪力螺栓的主要破坏形式为螺杆剪断和()。
A.螺杆压断
B.螺杆拉断
C.孔壁压坏