strong; 坚固
firm; stable; 稳固
firmly invite; 固请
resolutely refuse; firmly decline 固辞
It is just as it should be. 固当如此。
Admittedly we can make the journey by train, but there is no harm in our travelling by boat. 乘车固可,乘船亦无不可。
strengthen the dyke 固堤
It's not high mountains and deep valleys that best serve to defend a country. 固国不以山溪之险。
Gu Cheng 固乘
牛津高阶第八版
美国韦氏词典
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维基百科 (自由的百科全书)