A more thorough explanation:

Definition: To sustain means to support or maintain something, especially over a long period of time. It can also mean to endure or undergo something. In legal contexts, to sustain may also mean to uphold a ruling.

• She needed to sustain her energy throughout the marathon.
• The company was able to sustain its growth for several years.
• Despite the difficult circumstances, the community was able to sustain their hope for a better future.
• The judge sustained the objection made by the defense attorney.

The first three examples illustrate how sustain can mean to support or maintain something over a long period of time. In the first example, the runner needs to sustain her energy throughout the entire marathon. In the second example, the company is able to sustain its growth for several years. In the third example, the community is able to sustain their hope for a better future despite difficult circumstances.

The fourth example illustrates how sustain can be used in a legal context. In this case, the judge upheld the objection made by the defense attorney.