The investigations show that the secondarymaintenance for steel pipe piles by the methods of underwater coating and drainage covering ia an effective measures.
研究表明，采用水下涂料和排水护套法对钢管桩进行二次维护是行之可效的。
2
Paths and secondary roads were improved only at the request of communities who were willing to participate in construction and maintenance.
只有在那些愿意参与建设和保养公路的社区提出要求后，乡间小路和二级公路才有所改善。
3
Such artifacts are viewed as secondary, and therefore as a future maintenance burden.