一、二级焊缝不得有表面气孔、夹渣、( )、电弧擦伤等缺陷。
A.弧坑裂纹
B.油污
C.焊渣
参考答案:A
It is clear that some chemicals can damage the health of animals and humans. (1) , this is not the only problem that (2) be caused by the careless use of chemicals. Chemicals can also (3) the ecological balance of the environment. If the ecological balance is disturbed, the results can be (4) serious.The (5) of DDT illustrates the problem. DDT, a chemical which kills insects, at first seemed to be a perfect answer (6) many problems. It would control insects that caused dangerous diseases, (7) insects that caused billions of dollars of damage to crops every year. Governments permitted and even (8) the use of DDT. Farmers in many countries (9) to spray it on their crops. The (10) results were good. Damage to crops (11) down, and profits went up. However, the chemical had effects which the scientists didn’t see in (12) . First, it also killed insects which were the (13) enemies of the harmful insects and which were therefore beneficial to farmers. Second, and perhaps worse, DDT did not kill (14) harmful insect. A few insects had natural resistance to the chemical. They (15) and reproduced in large numbers. In a few years there were large numbers of insects which were not (16) by DDT, and there were (17) insects which Could act as natural (18) on these new "super-insects". Finally, it became clear that DDT was not solving the insect problem. In fact, it was making the problem worse. It (19) became necessary to find a second (20) for the effects of the first.
第(10)空应选择()
A.fast
B.immediate
C.moment
D.last
在工程评标过程中,符合性评审是指( )。
A.审查工程材料和机械设备供应的技术性能是否符合设计技术要求
B.对报价构成的合理性进行评审’
C.对施工方案的可行性进行评审
D.审查投标文件是否响应招标文件的所有条款和条件,有无显著的差异或保留