It's important to use a laxative only when necessary.

只有在必要时才使用泻药是很重要的。

Learn to say no when necessary.

学会在必要的时候说不。

I'd like to live a creative life and make changes when necessary as she did.

我想过一种有创造力的生活，并像她一样在必要时做出改变。

Use colors only when necessary.

只有必要的时候才使用颜色。

Arrange for packing when necessary.

当需要时，安排打包。

Schedule can be altered when necessary.

课程安排有可能根据需要做调整。

Work As Expediting Engineer When Necessary.

必要时充当监制工程师负责现场监制工作.

Please only use chicken wire when necessary!

请在非必要时不要使用铁鸡网!

Work as expediting engineer when necessary

必要时充当监制工程师负责现场监制工作

Wash well and use barrier creams when necessary.

好好洗手，必要时用护肤霜。