firm up
US /fɜːrm ʌp/
UK /fɜːrm ʌp/

短语动词
1.
2.
凝固, 变硬
to make something physically stronger or more solid
示例:
•
The concrete needs time to firm up before we can build on it.
混凝土需要时间凝固,然后我们才能在上面施工。
•
The jelly will firm up in the refrigerator.
果冻会在冰箱里凝固。
在 Lingoland 学习这个单词