可导致的

The first lesson is the easiest one in this b ook.

第一课是这本书最简单的一课。

Being considered as "common illness" or "frequently occurring disease", concrete rifts perplexed bridgework technician for a long time.

混凝土开裂可以说是"常见病"和"多发病"，长期困扰着桥梁工程技术人员。