增加困难 meaning in Chinese

multiply the difficulties

To sink under the weight was but to increase the weight .
在困难之中消沉下去就等于增加困难。
Where forests are concerned, the difficulty is increased by the longevity and competitive capacity of dominant tree species .
只要哪里涉及森林，就由于优势树种的长命和竞争力而增加困难。
The sclerotia can infect rice plant in 1 - 3cm depth of soil , bringing about a new complicated problems to contral the desease
菌核多次萌发特性和地下侵染能力使防治增加困难。
It ' s sample , straightforward texts and tasks and difficulty grdualy in creasing to bring in more complex structures
这一句我是这样理解：它简单，易懂的内容及作业然后逐步的增加困难度更复杂的结构。